Optical film

ABSTRACT

To provide an optical film excellent in suppression of light leakage in black display. An optical film having a first phase difference layer and a second phase difference layer, wherein the second phase difference layer has an optical property represented by the formula (3), the second phase difference layer has a thickness of 0.2 μm to 2.0 μm, and further, the optical film has optical properties represented by the formulae (1) and (2): 
         Re (450)/ Re (550)≦1.00  (1)
 
       1.00≦ Re (650)/ Re (550)  (2)
 
         nx≈ny&lt;nz   (3).

TECHNICAL FIELD

The present invention relates to an optical film.

BACKGROUND ART

In a flat panel display (FPD), members containing an optical film suchas polarization plates, phase difference plates and the like are used.As such an optical film, an optical film produced by coating acomposition containing a polymerizable liquid crystal on abase materialis known. For example, patent document 1 describes the optical filmshowing reverse wavelength dispersibility.

PRIOR ART DOCUMENT Patent Document

(Patent Document 1) Japanese Patent Application National Publication No.2010-537955

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

However, conventional optical films have not been sufficient in anoptical compensation property of suppressing light leakage in blackdisplay.

Means for Solving the Problem

The present invention includes the following inventions.

[1] An optical film having a first phase difference layer and a secondphase difference layer, wherein the second phase difference layer has anoptical property represented by the formula (3), the second phasedifference layer has a thickness of 0.2 μm to 2.0 μm, and further, theoptical film has optical properties represented by the formula (1) andthe formula (2)

Re(450)/Re(550)≦1.00  (1)

1.00≦Re(650)/Re(550)  (2)

nx≈ny<nz  (3)

(wherein, Re(450) represents the in-plane phase difference value at awavelength of 450 nm, Re(550) represents the in-plane phase differencevalue at a wavelength of 530 nm, and Re(650) represents the in-planephase difference value at a wavelength of 650 nm. nx represents theprincipal refractive index in a parallel to the film plane in an indexellipsoid formed by the phase difference layer. ny represents therefractive index in a direction parallel to the film plane andorthogonallly-crossing the direction of nx in an index ellipsoid formedby the phase difference layer. nz represents the refractive index in adirection vertical to the film plane in an index ellipsoid formed by thephase difference layer.).

[2] The optical film according to [1], wherein the first phasedifference layer has an optical property represented by the formula (4):

100<Re(550)<160  (4)

(wherein, Re(550) represents the same meaning as described above.).

[3] The optical film according to [1] or [2], wherein the first phasedifference layer has optical properties represented by the formula (1)fl and the formula (2):

Re(450)/Re(550)≦1.00  (1)

1.00≦Re(650)/Re(5.50)  (2)

(wherein, Re(450), Re(550) and Re(650) represent the same meaning asdescribed above.).

[4] The optical film according to any one of [1] to [3], wherein thefirst phase difference layer has a layer A having optical propertiesrepresented by the formulae (4), (6) and (7) and a layer B havingoptical properties represented by the formulae (5), (6) and (7):

100<Re(550)<160  (4)

200<Re(550)<320  (5)

Re(450)/Re(550)≧1.00  (6)

1.00≧Re650)/Re550)  (7)

(wherein, Re(450), Re(550) and Re(650) represent the same meaning asdescribed above.).

[5] The optical film according to [1] or [2], further having a thirdphase difference layer, wherein the third phase difference layer has anoptical property represented by the formula (5):

200<Re (330)<320  (5)

(wherein, Re(550) represents the same meaning as described above.). [6]The optical film according to [5], wherein the first phase differencelayer and the third phase difference layer have optical propertiesrepresented by the formula (6) and the formula (7):

Re(450)/Re(550)≧1.00  (6)

1.00≧RE(650)/Re(550)  (7)

(wherein, Re(450), Re(550) and Re(650) represent the same meaning asdescribed above.).

[7] The optical film according to [5] or [6], wherein third phasedifference layer is a coating layer formed by polymerizing at least onepolymerizable liquid crystal.

[8] The optical film according to any one of [5] to [7], wherein thethird phase difference layer has a thickness of 5 μm or less.

[9] The optical film according to any one of [5] to [8], wherein thethird phase difference layer is formed on an orientation film.

[10] The optical film according to any one of [1] to [9], wherein thefirst phase difference layer is a coating layer formed by polymerizingat least one polymerizable liquid crystal.

[11] The optical film according to any one of [1] to [10], wherein thesecond phase difference layer is a coating layer formed by polymerizingat least one polymerizable liquid crystal.

[12] The optical film according to any one of [1] to [11], wherein thefirst phase difference layer has a thickness of 1.0 μm to 7.5 μm.

[13] The optical film according to any one of [1] to [12], wherein thesecond phase difference layer has a thickness of 0.3 μm to 1.0 μm.

[14] The optical film according to any one of [1] to [13], wherein eachof the first phase difference layer and the second phase differencelayer has a thickness of 2.0 μm or less.

[15] The optical film according to any one of [1] to [14], wherein thefirst phase difference layer is formed on an orientation film.

[16] The optical film according to any one of [1] to [15], wherein thesecond phase difference layer is formed on an orientation film.

[17] The optical film according to [9], [15] or [16], wherein theorientation film is an orientation film having an orientation regulationforce generated by photoirradiation.

[18] The optical film according to [9], [15] or [16], wherein theorientation film is an orientation film generating a verticalorientation regulation force.

[19] The optical film according to any one of [15] to [18], wherein theorientation film has a thickness of 500 nm or less.

[20] The optical film according to any one of [1] to [19], wherein thefirst phase difference layer is formed via or not via an orientationfilm on a base material, and the second phase difference layer is formedvia or not via an orientation film on the first phase difference layer.

[21] The optical film according to any one of [1] to [20], wherein thesecond phase difference layer is formed via or not via an orientationfilm on a base material, and the first phase difference layer is formedvia or not via an orientation film on the second phase difference layer.

[22] The optical film according to any one of [5] to [21], whereinhaving the first phase difference layer, the second phase differencelayer and the third phase difference layer in this order.

[23] The optical film according to any one of [20] to [22], whereinhaving a protective layer between the first phase difference layer andthe second phase difference layer.

[24] The optical film according to [22], wherein having a protectivelayer between the second phase difference layer and the third phasedifference layer.

[25] The optical film according to any one of [1] to [19], wherein thefirst phase difference layer is formed via or not via an orientationfilm on one surface of a base material, and the second phase differencelayer is formed via or not via an orientation film on the other surfaceof a base material.

[26] The optical film according to [4], wherein the layer A is a coatinglayer formed by polymerizing at least one polymerizable liquid crystal.

[27] The optical film according to [4], wherein the layer B is a coatinglayer formed by polymerizing at least one polymerizable liquid crystal.

[28] The optical film according to [4], wherein the layer A has athickness of 0.5 μm to 2.5 μm.

[29] The optical film according to [4], wherein the layer B has athickness of 0.5 μm to 5.0 μm.

[30] The optical film according to [4], wherein each of the layer A andthe layer B has a thickness of 2.5 μm or less.

[31] The optical film according to [4], wherein the layer A is formedvia or not via an orientation film on a base material, the layer B isformed via or not via an orientation film on the layer A, and the secondphase difference layer is formed via or not via an orientation film onthe layer B.

[32] The optical film according to [4], wherein the layer B is formedvia or not via an orientation film on a base material, the layer A isformed via or not via an orientation film on the layer B, and the secondphase difference layer is formed via or not via an orientation film onthe layer A.

[33] The optical film according to [4], wherein the second phasedifference layer is formed via or not via an orientation film on a basematerial, the layer A is formed via or riot via an orientation film onthe second phase difference layer, and the layer B is formed via or notvia an orientation film on the layer A.

[34] The optical film according to [4], wherein the second phasedifference layer is formed via or not via an orientation film on a basematerial, the layer B is formed via or not via an orientation film onthe second phase difference layer, and the layer A is formed via or notvia an orientation film on the layer B.

[35] The optical film according to [4], wherein the layer A is formedvia or not via an orientation film on one surface of a base material,the layer B is formed via or not via an orientation film on the layer A,and the second phase difference layer is formed via or not via anorientation film on the other surface of a base material.

[36] The optical film according to [4], wherein the layer B is formedvia or not via an orientation film on one surface of a base material,the layer A is formed via or not via an orientation film on the layer B,and the second phase difference layer is formed via or not via anorientation film on the other surface of a base material.

[37] The optical film according to any one of [31] to [36], whereinhaving a protective layer between the layer A and the layer B.

[38] The optical film according to [5], wherein the first phasedifference layer is formed via or not via an orientation film on a basematerial, the second phase difference layer is formed via or not via anorientation film on the first phase difference layer, and the thirdphase difference layer is formed via or not via an orientation film onthe second phase difference layer.

[39] The optical film according to [5], wherein the third phasedifference layer is formed via or not via an orientation film on a basematerial, the second phase difference layer is formed via or not via anorientation film on the third phase difference layer, and the firstphase difference layer is formed via or not via an orientation film onthe second phase difference layer.

[40] The optical film according to [5], wherein the first phasedifference layer is formed via or not via an orientation film on onesurface of a base material, the second phase difference layer is formedvia or not via an orientation film the first phase difference layer, andthe third phase difference layer is formed via or not via an orientationfilm on the other surface of a base material.

[41] The optical film according to [5], wherein the second phasedifference layer is formed via or not via an orientation film on onesurface of a base material, the first phase difference layer is formedvia or not via an orientation film on the second phase difference layer,and the third phase difference layer is formed via or not via anorientation film on the other surface of a base material.

[42] The optical film according to [5], wherein the third phasedifference layer is formed via or not via an orientation film on onesurface of a base material, the second phase difference layer is formedvia or not via an orientation film on the third phase difference layer,and the first phase difference layer is formed via or not via anorientation film on the other surface of a base material.

[43] The optical film according to [5], wherein the second phasedifference layer is formed via or not via an orientation film on onesurface of a base material, the third phase difference layer is formedvia not via an orientation film on the second phase difference layer,and the first phase difference layer is formed via or not via anorientation film on the other surface of a base material.

[44] A circular polarization plate having the optical film according toany one of [1] to [43] and a polarization plate.

[45] The circular polarization plate according to [44], wherein theoptical and the polarization plate are pasted together with an activeenergy ray curable adhesive or an aqueous adhesive.

[46] An organic display having the circular polarization plate accordingto [44] or [45].

[47] A touch panel display having the circular polarization plateaccording to [44] or [45].

Effect of the Invention

According to the present invention, an optical film excellent insuppression of light leakage in back display can be provided.

BRIEF EXPLANATION OF DRAWINGS

FIG. 1 is a schematic cross-sectional an optical film of the presentinvention.

FIG. 2 is a schematic cross-sectional view of an optical film of thepresent invention.

FIG. 3 is a schematic cross-sectional view of a circular polarizationplate containing an optical film of the present invention.

FIG. 4 is a schematic cross-sectional view of a circular polarizationplate containing an optical film of the present invention.

FIG. 5 is a schematic cross-sectional view of an organic EL displaycontaining an optical film of the present invention.

FIG. 6 is a schematic view of an organic EL display containing anoptical film of the present invention.

MODES FOR CARRYING OUT THE INVENTION

The optical film of the present invention (hereinafter, referred to aspresent optical film in some cases) has a first phase difference layerand a second phase difference layer. The present optical film may alsohave a third phase difference layer. The first phase difference layer,the second phase difference layer and the third phase difference layerare a phase difference layer having certain optical properties, and thefirst phase difference layer, the second phase difference layer and thethird phase difference layer may each be composed of two or more.

The present optical film has optical properties represented by theformula (1) and the formula (2). For the present optical film to havesuch optical properties, it is permissible that the first phasedifference layer, the second phase difference layer or the third phasedifference layer has optical properties represented by the formula (1)and the formula (2), or optical properties represented by the formula(1) and the formula (2) are manifested by combining at least twoselected from the first phase difference layer, the second phasedifference layer and the third phase difference layer.

Re(450)/Re(550)≦1.00  (1)

1.00≦Re(650)/Re(550)  (2)

In the present specification, Re(450) represents the in-plane phasedifference value at a wavelength of 450 nm, Re (550) represents thein-plane phase difference value at a way length of 550 nm, and Re(650)represents the in-plane phase difference value at a wavelength of 660nm.

[Phase Difference Layer]

As the phase difference layer, for example, layers formed bypolymerizing a polymerizable liquid crystal and drawn films are listed.The optical properties of a phase difference layer can be regulated bythe orientation state of a polymerizable liquid crystal or a drawingmethod of a drawn film.

<Layer Formed by Polymerizing Polymerizable Liquid Crystal>

In the present invention, orientation of the optical axis of apolymerizable liquid crystal horizontally to the base material plane isdefined as horizontal orientation, and orientation of the optical axisof a polymerizable liquid crystal vertical to the base material plane isdefined as vertical orientation. The optical axis denotes a direction inwhich the cross-section of an index ellipsoid formed by orientation of apolymerizable liquid crystal cut in a direction orthogonally crossingthe optical axis is circle, namely a direction in which refractiveindices in three directions are all equivalent.

The polymerizable liquid crystal includes rod-shaped polymerizableliquid crystals and disk-shaped polymerizable liquid crystals.

When the rod-shaped polymerizable liquid crystal is orientedhorizontally to or oriented vertically to a base material, the opticalaxis of the polymerizable liquid crystal coincides with the direction ofthe long axis of the polymerizable liquid crystal.

When the disk-shaped polymerizable liquid crystal is oriented, theoptical axis of the polymerizable liquid crystal exists in a directionorthogonally crossing the disk surface of the polymerizable liquidcrystal.

The slow axis direction of a drawn film varies depending on a drawingmethod, and the slow axis and the optical axis are determined dependingon its drawing method such as uniaxial, biaxial or diagonal drawing endthe like.

For the layer formed by polymerizing a polymerizable liquid crystal tomanifest in-plane phase difference, it is advantageous that apolymerizable liquid crystal is oriented to a suitable direction. Whenthe polymerizable liquid crystal is in the form of a rod, in-plane phasedifference is manifested by orienting the optical axis of the polymerizeliquid crystal horizontally to the base material plane, and in thiscase, the direction of the optical axis and the direction of the slowaxis coincide with each other. When the polymerizable liquid crystal isin the form of a disk, in-plane phase difference is manifested byorienting the optical axis of the polymerizable liquid crystalhorizontally to the base material plane, and in this case, the opticalaxis and the slow axis cross orthogonally. The orientation state of apolymerizable liquid crystal can be adjusted by a combination of theoriented film and the polymerizable liquid crystal.

The in-plane phase difference value of a phase difference layer can beregulated by the thickness of the phase difference layer. Since thein-plane phase difference value is determined by the formula (10), it isadvantageous to regulate Δn(λ) and the film thickness d for obtainingthe desired in-plane phase difference value (Re(λ)).

Re(λ)=d×Δn(λ)  (10)

In the formula, Re(λ) represents the in-plane phase difference value ata wavelength of λ nm, d represents the film thickness, and Δn(λ)represents the birefringence at a wavelength of λ nm.

The birefringence Δn(λ) is obtained by measuring the in-plane phasedifference value and dividing the measured value by the thickness of aphase difference layer. The specific measuring method is shown inexamples, and on this occasion, the substantial property of a phasedifference layer can be measured by measuring one formed on a basematerial having itself no in-plane phase difference such as a glass baseplate.

In the present invention, refractive indices in three directions in anindex ellipsoid formed by orientation of a polymerizable liquid crystalor drawing of a film are represented by nx, ny and nz. nx represents theprincipal refractive index in a direction parallel to the film plane inan index ellipsoid formed by a phase difference layer. ny represents therefractive index in a direction parallel to the film plane andorthogonally-crossing the direction of the principal refractive index inan index ellipsoid formed by the phase difference layer. nz representsthe refractive index in a direction vertical to the film plane in anindex ellipsoid formed by a phase difference layer.

When the optical axis of a rod-shaped polymerizable liquid crystal isoriented horizontally to the base material plane, the refractive indexcorrelation of the resultant phase difference layer is nx>ny≈nz(positive A plate) and the axis of the direction of nx in an indexellipsoid and the slow thereof coincide with each other.

When the optical axis of a disk-shaped polymerizable liquid crystal isoriented horizontally to the base material plane, the refractive indexcorrelation of the resultant phase difference layer is nx<ny≈nz(negative A plate) and the axis of the direction of ny in an indexellipsoid and the slow axis thereof coincide with each other.

For the layer formed by polymerizing a polymerizable liquid crystal tomanifest phase difference in the thickness direction, it is advantageousto orient the polymerizable liquid crystal in a suitable direction. Inthe present invention, manifestation of phase difference in thethickness direction is defined as indicating a property under which Rth(phase difference value in thickness direction) is negative in theformula (20). Rth can be calculated from the phase difference value(R40) measured with inclining an in-plane fast axis at an angle of 40°as an inclined axis and from the in-plane phase difference value (Re).That is to say, Rth can be calculated by determining nx, ny and nzaccording to the following formulae (21) to (23) from Re, R40, d(thickness of phase difference layer) and n0 (average refractive indexof phase difference layer) and substituting them into the formula (20).

Rth=[(nx+ny)/2−nz]×d  (20)

Re= 9 nx−ny)×d  (21)

R ₄₀=(nx−ny′)×d/cos(φ)  (22)

(nx+ny+nz)/3=n0  (23)

Here,

φ=sin⁻¹[sin(40°)/n0]

ny′=ny×nz/[ny ²×sin²(φ)+nz ²×cos²(φ)]^(1/2)

nx, ny and nz are as defined above.

When the polymerizable liquid crystal is in the form of a rod, phasedifference in the thickness direction is manifested by orienting theoptical axis of the polymerizable liquid crystal vertically to the basematerial plane. When the polymerizable liquid crystal is in the form ofa disk, phase difference in the thickness direction is manifested byorienting the optical axis of the polymerizable liquid crystalhorizontally to the base material lane. In the case of a disk-shapedpolymerizable liquid crystal, the optical axis of the polymerizableliquid crystal is parallel to the base material plane, therefore, whenRe is determined, the thickness is fixed, thus Rth is unambiguouslydetermined, while in the case of a rod-shaped polymerizable liquidcrystal, the optical axis of the polymerizable liquid crystal isvertical to the base material plane, therefore, Rth can be regulatedwithout varying Re by regulating the thickness of a phase differencelayer.

When the optical axis of a rod-shaped polymerizable liquid crystal isoriented vertically to the base material plane, the refractive indexcorrelation of the resultant phase difference layer is nx≈ny<nz(positive C plate), and the axis of the direction of nz in an indexellipsoid and the slow axis direction thereof coincide with each other.

When the optical axis of a disk-shaped polymerizable liquid crystal isoriented parallel to the base material plane, the refractive indexcorrelation of the resultant phase difference layer is nx<ny≈nz(negative A plate), and the axis of the direction of ny in an indexellipsoid and the slow axis direction thereof coincide with each other.

<Polymerizable Liquid Crystal>

The polymerizable liquid crystal is a compound having a polymerizablegroup and having liquid crystallinity. The polymerizable group denotes agroup correlated with a polymerization reaction, and is preferably aphotopolymerizable group. Here, the photopolymerizable group denotes agroup capable of being correlated with a polymerization reaction owingto an active radical, an acid and the like generated from aphotopolymerization initiator described later. The polymerizable groupincludes a vinyl group, a vinyloxy group, a 1-chlorovinyl group, anisopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, amethacryloyloxy group, an oxiranyl group, an oxetanyl group and thelike. Of them, an acryloyloxy group, a methacryloyloxy group, a vinyloxygroup, an oxiranyl group and an oxetanyl group are preferable, and anacryloyloxy group in more preferable. The crystallinity of thepolymerizable liquid crystal may be thermotropic or lyotropic, and thethermotropic liquid crystal maybe, if classified depending on the degreeof order, a nematic liquid crystal or a smectic liquid crystal.

The rod-shaped polymerizable liquid crystal includes, for example,compounds represented by the following formula (A) (hereinafter,referred to as polymerizable liquid crystal (A) in some cases) andcompounds containing a group represented by the following formula (X)(hereinafter, referred to as polymerizable liquid crystal (B) in somecases).

[in the formula (A),

X¹ represents an oxygen atom, a sulfur atom or NR1—R1 represents ahydrogen atom or an alkyl group having 1 to 4 carbon atoms.

Y¹ represents a mono-valent aromatic hydrocarbon group having 6 to 12carbon atoms and optionally carrying a substituent or a mono-valentaromatic heterocyclic group having 3 to 12 carbon atoms and optionallycarrying a substituent.

Q³ and Q⁴ represent each independently a hydrogen atom, a mono-valentaliphatic hydrocarbon group having 1 to 20 carbon atoms and optionallycarrying a substituent, a mono-valent alicyclic hydrocarbon group having3 to 20 carbon atoms, a mono-valent aromatic hydrocarbon group having 6to 20 carbon atoms and optionally carrying a substituent, a halogenatom, a cyano group, a nitro group, —NR2R3 or SR2, alternatively Q³ andQ⁴ are mutually bonded to form an aromatic ring or an aromatic heteroring together with a carbon atom to which they are attached. R2 and R3represent each independently a hydrogen atom or an alkyl group having 1to 4, carbon atoms.

D¹ and D² represent each independently a single bond, —C(═O)—O—,—C(═S)—O—, —CR4R5—, —CR4R5—CR6R7—, —O—CR4R5—, —CR4R5—O—Cr6R7—,—CO—O—CR4R5—, —O—CO—CR4R5—, —CR4R5—O—CO—CR6R7—, —CR4R5—CO—O—CR6R7— orNR4—CR5R6— or CO—NR4—.

R4, R5, R6 and R7 represent each independently a hydrogen atom, afluorine atom or an alkyl group having 1 to 4 carbon atoms.

G¹ and G² represent each independently a di-valent alicyclic hydrocarbongroup having 5 to 8 carbon atoms, a methylene group constituting thealicyclic hydrocarbon group may be replaced by an oxygen atom, a sulfuratom or NH—, and a methine group constituting the alicyclic hydrocarbongroup may be replaced by a tertiary nitrogen atom.

L¹ and L² represent each independently a mono-valent organic group, andat least one of L¹ and L² has a polymerizable group.]

In the polymerizable liquid crystal (A), L¹ is preferably a grouprepresented by the formula (A1), and L² is preferably a grouprepresented by the formula (A2).

P1—F1—(B1—A1)k—E1—  (A1)

P2—F2—(B2—A2)1—E2—  (A2s)

[in the formula (A1) and the formula (A2),

B1, B2, E1 and E2 represent each independently —CR4R5—, —CH2—CH2—, —O—,—S—, —CO—O—, —O—CO—O—, —SO—O—, —O—CS—O—, —CO—NR1—, —O—CH2—, —S—CH2— or asingle bond.

A1 and A2 represent each independently a di-valent alicyclic hydrocarbongroup having 5 to 8 carbon atoms or a di-valent aromatic hydrocarbongroup having 6 to 18 carbon atoms, a methylene group constituting thealicyclic hydrocarbon group may be replaced by an oxygen atom, a sulfuratom or NH—, and a methine group constituting the alicyclic hydrocarbongroup may be replaced by a tertiary nitrogen atom.

k and l represent each independently an integer of 0 to 3.

F1 and F2 represent a di-valent aliphatic hydrocarbon group having 1 to12 carbon atoms

P1 represents a polymerizable group.

P2 represents a hydrogen atom or a polymerizable croup.

R4 and R6 represent each independently a hydrogen atom, a fluorine atomor an alkyl group having 1 to carbon atoms.]

The preferable polymerizable liquid crystal (A.) includes compoundsdescribed in Japanese Patent Application National Publication No.2011-207765.

P11—B11—E11—B12—A11—B13—  (X)

[in the formula (X), P11 represents a polymerizable group.

A11 represents a di-valent alicyclic hydrocarbon group or a di-valentaromatic hydrocarbon group. A hydrogen atom contained in the di-valentalicyclic hydrocarbon group and the di-valent aromatic hydrocarbon groupmay be substituted by a halogen atom, an alkyl group having 1 to 6carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano groupor a nitro group, and a hydrogen atom contained in the alkyl coup having1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms maybe substituted by a fluorine atom.

B11 represents —O—, —S,—, —CO—9—, —O—CO—, —O—CO—O—, —CO—NR16—,—NR16—CO—, —CO—, —CS— or a single bond. R16 represents a hydrogen atomor an alkyl group having 1 to 6 carbon atoms.

B12 and B13 represent each independently —C≡C—, —CH═CH—, —CH2—CH2—, —O—,—S—, —C(═O)—, —C(═)—O—, —O—C(═O)—, —O—C(═O)—O—, —CH═N—, —N═CH—, —N═N—,—C(═O)—NR16—, —NR16—C(═O)—, —OCH2—, —OCF2—, —CH2O—, —CF2O—,—CH═CH—C(═O)—O—, —O—C(═O)—CH═CH— or a single bond.

E11 represents an alkanediyl group having 1 to 12 carbon atoms, ahydrogen atom contained in the alkanediyl group may be substituted by analkoxy group having 1 to 5 carbon atoms, and a hydrogen atom containedin the alkoxy group may be substituted by a halogen atom. —CH₂—constituting the alkanediyl group may be replaced by —O— or CO—.]

The number of carbon atoms of the aromatic hydrocarbon group and thealicyclic hydrocarbon group represented by A11 is preferably in therange of 3 to 18, more preferably in the range of 5 to 12, particularlypreferably 5 or 6. A11 is preferably a cyclohexane-1,4-diyl group or a1,4-phenylene group.

E11 is preferably a linear alkanediyl group having 1 to 12 carbon atoms.—CH₂— constituting the alkanediyl group may be replaced by —O—.

Specifically listed are linear alkanediyl groups having 1 to 12 carbonatoms such as a methylene group, an ethylene group, a propane-1,3-diylgroup, a butane-1,4-diyl group, a pentane-1,5-diyl group, ahexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diylgroup, a nonane-1,9-diyl group, a decane-1,10-diyl group, anundecane-1,11-diyl group, a dodecane-1,12-diyl group and the like;—CH2—CH2—O—CH2—CH2—, —CH2—CH2—O—CH2—CH2—O—CH2—CH2— andCH2—CH2—O—CH2—CH2—O—CH2—CH2—O—CH2—CH2—, and the like.

B11 is more preferably —O—, —S—, —CO—O— or —O—CO—, and of them, —CO—O—is more preferably.

B12 and E13 preferably represent each independently —O—, —S—, —C(═O)—,—C(═O)—O—, —O—C(═O)— or —O—C(═O)—O—, and of them, —O— or —O—C(═O)—O— ismore preferable.

The polymerizable group represented by P11 is preferably a radicalpolymerizable group or a cation polymerizable group because of highpolymerization reactivity, particularly, high photopolymerizationreactivity, and the polymerizable group includes preferably groupsrepresented by the following formula (P-11) to (P-15) since handlingthereof is easy, and additionally, production itself of a liquid crystalcompound is also easy.

[in the formula (P-11) to (P-15),

R¹⁷ and R²¹ represent each independently an alkyl group having 1 to 6carbon atoms or a hydrogen atom.]

Specific examples of the group represented by the formulae (P-11) to(P-15) include groups represented by the following formulae (P-16) to(P-20).

P11 is preferably a group represented by the formulae (P-14) to (P-20),and a vinyl group, a p-stilbene, an epoxy group or an oxetanyl group ismore preferable.

It is further preferable that the group represented by P11—B11— is anacryloyloxy group or a methacryloyloxy group.

The polymerizable liquid crystal (B) includes compounds represented bythe formula (I), the formula (II), the formula (III), the formula (IV),the formula (V) or the formula (VI).

P11—B11—E11—B12—A11—B13—A12—B14—A13—B15—A14—B16—E12—B17—P12  (I)

P11—B11—E11—B12—A11—B13—A12—B14—A13—B15—A14—F11  (II)

P11—B11—E11—B12—A11—B13—A12—B14—A13—B15—E12—B17—P12  (III)

P11—B11—E11—B12—A11—B13—A12—B14—A13—F11  (IV)

P11—B11—E11—B12—A11—B13—A12—B14—E12—B17—P12—  (V)

P11—B11—E11—B12—A11—B13—A12—F11  (VI

(wherein,

A12 to A14 are each independently as defined for A11, B14 to B16 areeach independently as defined for B12, B17 is as defined for B11, andB12 is as defined for E11.

F11 represents a hydrogen atom, an alkyl group having 1 to 13 carbonatoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, anitro group, a trifluoromethyl group, dimethylamino group, a hydroxygroup, a methylol group, a formula group, a sulfo group (—SO₃H), acarboxy group, an alkoxycarbonyl group having 1 to 10 carbon atoms or ahalogen atom, and —CH₂— constituting the alkyl group and the alkoxygroup may be replaced by —O—.)

Specific examples of the polymerizable liquid crystal (B) includecompounds having a polymerizable group among compounds described in“3.8.6 Network (perfect cross-linked);” And “6.5.1 Liquid CrystalMaterial b. Polymerizable nematic liquid crystal material” of LiquidCrystal Handbook (Liquid Crystal Handbook Editorial Committee, ed.,published on Oct. 30, 2000 by Maruzen), and polymerizable liquidcrystals described in JP-A No. 2010-31223, JP-A No. 2010-270108, JP-ANo. 2011-8360 and JP-A 2011-207765.

Specific examples of the polymerizable liquid crystal (B) includecompounds represented by the following formulae (I-1) to (I-4), formulae(II-1) to (II-4), formulae (III-1) to (III-26), formulae (IV-1) to(IV-26), formulae (V-1), to (V-2) and formulae (VI-1) to (VI-6). In thefollowing formulae, k1 and k2 represent each independently an integer of2 to 12. These polymerizable liquid crystals (B) are preferable from thestandpoint of easiness of synthesis thereof or easy availability.

The disk-shaped polymerizable liquid crystal includes, for example,compounds containing a group represented by the formula (W)(hereinafter, referred to as polymerizable liquid crystal (C) in somecases).

[in the formula (W), R⁴⁰ represents the following formula (W-1) toformula (W-5).

X⁴⁰ and Z⁴⁰ represent an alkanediyl group having 1 to 12 carbon atoms, ahydrogen atom contained in the alkanediyl group may be substituted by analkoxy group having 1 to 5 carbon atoms, and a hydrogen atom containedin the alkoxy group may be substituted by a halogen atom. —CH₂—constituting the alkanediyl group may be replaced by—O— or CO—.

Specific examples of the polymerizable liquid crystal (C) includecompounds described in “6.5.1 Liquid Crystal Material b. Polymerizablenematic liquid crystal material Fig. 6.21” of Liquid Crystal Handbook(Liquid Crystal Handbook Editorial Committee, ed., published on Oct. 30,2000 by Maruzen), and polymerizable liquid crystals described in JP-ANo. 7-258170, JP-A No. 7-30637, JP-A No. 7-309807 and JP-A No. 8-231470.

A phase difference layer having optical properties represented by theformula (1) and the formula 2) is obtained by polymerizing apolymerizable liquid crystal having a specific structure, by drawing apolymer film having a specific structure, or by combining a layer havingoptical properties represented by the formulae (4), (6) and (7) with alayer having optical properties represented by the formulae (5), (6) and(7) in a specific slow axial relationship.

Re(450)/Re(550)≦1.00  (1)

1.00≦Re(650)/Re(550)  (2)

100<Re(550)<160  (4)

200<Re(550)<320  (5)

Re(450)/Re(550)≧1.00  (6)

1.00≧Re(650)/Re(550)  (7)

The present optical film having optical properties represented by theformula (1) and the formula (2) can be obtained by allowing a phasedifference layer to have optical properties represented by the formula(1) and the formula (2). If the present optical film has opticalproperties represented by the formula (1) and the formula 2), a uniformpolarization conversion property is obtained for lights of variouswavelengths in the visible light range and light leakage of a displaysuch as an organic EL display or the like in black display can besuppressed.

The above-described polymerizable liquid crystal having a specificstructure includes, for example, the above-described polymerizableliquid crystal (A). A phase difference layer having optical propertiesrepresented by the formula (1) and the formula (2) is obtained byorienting the polymerizable liquid crystal (A) so that the optical axisis horizontal to the base material plane, and a phase difference layerhaving a desired in-plane phase difference value such as, for example,an optical property represented by the formula (4) or the like can beobtained by additionally regulating the film thickness according to theabove-described formula (10).

100<Re(550)<160  (4)

The method of combining a layer having optical properties represented bythe formulae (4), (6) and (7) with a layer having optical propertiesrepresented by the formula (5), (6) and (7) in a specific slow axialrelationship includes well-known methods.

For example, JP-A No. 10-68816 and JP-A No. 10-90521 disclose a phasedifference film obtained by laminating two polymer films showinganisotropy. For example, JP-A No. 2001-4837, JP-A No. 2001-21720 andJP-A No. 2000-206331 disclose a phase difference film having at leasttwo phase difference layers each composed of a liquid crystal compound.It is also possible that one of these two phase difference layers is apolymer film and the other is a phase difference layer composed of aliquid crystal compound.

The above-described phase difference layer having optical propertiesrepresented by the formula (6) and the formula (7) can be obtained bywell-known methods. That is to say, a phase difference layer obtained bythe other method than the method of obtaining the above-described phasedifference layer having optical properties represented by the formula(1) and the formula (2) generally has optical properties represented bythe formula (6) and the formula (7).

<Drawn Film>

The drawn film is usually obtained by drawing a base material. In amethod of drawing a base material, for example, a roll carrying a basematerial wound on the roll (wound body) is prepared, the base materialis continuously wound off from such a wound body, and the be materialwound off is conveyed to a heating furnace. The set temperature of aheating furnace is in the range from the approximate glass transitiontemperature (° C.) of the base material to [glass transitiontemperature+100](° C.), preferably in the range from the approximateglass transition temperature (° C.) of the base material to [glasstransition temperature+50](° C.). In the heating furnace, a uniaxial orbiaxial hot drawing treatment is conducted while controlling theconveying direction and tension and making inclination at any angle, inperforming drawing to the traveling direction of the base material or toa direction orthogonally crossing the traveling direction. The drawingmagnification is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

The method of drawing in an oblique direction is not particularlyrestricted providing that the orientation axis can be continuouslyinclined at desired angle, and a known drawing method can be adopted.Such a drawing method includes, for example, methods described in JP-ANo. 50-83482 and JP-A No. 2-113920. When a film is endowed with a phasedifference nature by performing drawing, the thickness after drawing isdetermined by the thickness before drawing and drawing magnification.

The drawn film having phase difference in the thickness directionincludes, for example, drawn films having refractive index correlationof nx<ny<nz described in JP-A No. 2008-129465 and known multi-layeredextruded films. Even the film having refractive index correlation ofnx<ny<nz can obtain the same effect as in the case of nx≈ny<nz since oris relatively larger.

The in-plane phase difference value of a drawn film and the phasedifference value in the thickness diction thereof can be regulated byΔn(λ) and film thickness d as in the case with the layer formed bypolymerizing a polymerizable liquid crystal.

The above-described drawn film obtained by drawing a polymer film havinga specific structure and having optical properties represented by theformula (1) and the formula (2) includes, for example, commerciallyavailable drawn films composed of a polycarbonate resin, specifically,“PURE-ACE (registered trademark) WR” (manufactured by Teijin Limited)and the like.

The above-described base material is usually a transparent basematerial. The transparent base material denotes a base material havingtransparency allowing transmission of light, especially visible light,and the transparency is a property giving a transmittance of 80% or morefor light beams ranging from a wavelength of 380 nm to 780 nm. Thetransparent base material includes, specifically, transparent resin basematerials. The resin constituting the transparent resin base materialincludes polyolefins such as polyethylene, polypropylene and the like;cyclic olefin resins such as norbornene polymers and the like; polyvinylalcohol; polyethylene terephthalate; polymethacrylates; polyacrylates;cellulose esters such as triacetylcellulose, diacetylcellulose,cellulose acetate propionate and the like; polyethylene naphthalate;polycarbonates; polysulfones; polyether sulfones; polyether ketones;polyphenylene sulfide and polyphenylene oxide. Preferable from thestandpoint of easy availability and transparency are polyethyleneterephthalate, polymethacrylates, cellulose esters, cyclic olefin resinsor polycarbonates.

The cellulose ester is obtained by esterifying part or all of hydroxylgroups contained in cellulose, and available easily from the market.Also the cellulose ester base material is available easily from themarket. The commercially available cellulose ester base materialincludes, for example “Fujitack (registered trademark) film” (FUJIFILMCorporation); “KC8UX2M”, “KC8UY” and “KC4UY” (Konica Minolta) OptoProducts Co., Ltd.) and the like

The polymethacrylates and the polyacrylates (hereinafter,polymethacrylates and polyacrylates are referred to collectively as(meth)acrylic resins in some cases) are available easily from themarket.

The (meth)acrylic resin includes, for example, homopolymers of alkylmethacrylates or alkyl acrylates, copolymers of alkyl methacrylates andalkyl acrylates, and the Like. The alkyl methacrylate includes,specifically, methyl methacrylate, ethyl methacrylate, propylmethacrylate and the like, and the alkyl acrylate includes,specifically, methyl acrylate, ethyl acrylate, propyl acrylate and thelike, respectively. As the (meth)acrylic resin, those commerciallymarketed as general-purpose (meth)acrylic resin can be fused. As the(meth)acrylic resin, those called an impact-resistant (meth)acrylicresin may be used.

For further improvement in mechanical strength, it is also preferablethat rubber particles are contained in a (meth)acrylic resin. The rubberparticles are preferably acrylic rubber particles. Here, the acrylicrubber particles are particles having rubber elasticity obtained bypolymerizing an acrylic monomer containing as the main component analkyl acrylate such as butyl acrylate and 2-ethylhexyl acrylate in thepresence of a poly-functional monomer. The acrylic rubber particle maybe composed of a single layer formed with such particles having rubberelasticity, or a multi-layered structure having at least one rubberelastic layer. The acrylic rubber particles having a multi-layeredstructure include those in which particles having rubber elasticity asdescribed above are contained as the nucleus and its periphery iscovered with a hard alkyl methacrylate polymer, those in which a hardalkyl methacrylate polymer is contained as the nucleus and its peripheryis covered with an acrylic polymer having rubber elasticity as describedabove, those in which the periphery of a hard nucleus is covered with arubber elastic acrylic polymer and its periphery is further covered witha hard alkyl methacrylate polymer, and the like. The rubber particlesformed with an elastic layer have its average diameter usually in therange of about 50 nm to 400 nm.

The content of rubber particles in (meth)acrylic resin is usually about5 to 50 parts by mass with respect to 100 parts by mass of the(meth)acrylic resin. Since a (meth)acrylic resin and acrylic rubberparticles are commercially marketed in the state of a mixture of them,commercially available products thereof can be used. Examples ofcommercially available products of a (meth)acrylic resin containingblended acrylic rubber particles include “HT55X” and “Tekunoroi S001”marketed from Sumitomo Chemical Co., Ltd., and the like. “TekunoroiS001” is marketed in the form of a film.

The cyclic olefin resin is available easily from the market. Thecommercially available cyclic olefin resin includes “Topas” (registeredtrademark) [Ticona Germany)], “ARTON” (registered trademark) [JSRCorporation], “ZEONOX” (registered trademark) [ZEON Corporation],“ZEONEX” (registered trademark) [ZEON Corporation] and “APEL”(registered trademark) [Mitsui Chemicals, Inc.]. Such a cyclic olefinresin can be processed by known means such as, for example, a solventcasting method, a melt extrusion method and the like, to obtain a basematerial. Commercially available cyclic olefin resin base materials canalso be used. The commercially available cyclic olefin resin basematerial includes “Esushina” (registered trademark) [Sekisui ChemicalCo., Ltd.], “SCA40” (registered trademark) [Sekisui Chemical Co., Ltd.],“ZEONOR FILM” (registered trademark) [Optes Co., Ltd.] and “ARTON FILM”(registered trademark) [JSR Corporation].

When the cyclic olefin resin is a copolymer of a cyclic olefin and alinear olefin or an aromatic compound having a vinyl group, the contentproportion of constituent units derived from the cyclic olefin isusually 50 mol % or lees, preferably in the range of 15 to 50 mol % withrespect to all constituent units of the copolymer. The linear olefinincludes ethylene and propylene, and the aromatic compound having avinyl group includes styrene, α-methylstyrene and alkyl-substitutedstyrene. When the cyclic olefin resin is a ternary copolymer composed ofa cyclic olefin, a linear olefin and an aromatic compound having a vinylgroup, the content proportion of constituent units derived from thelinear olefin is usually 5 to 80 mol % with respect to all constituentunits of the copolymer, and the content proportion of constituent unitsderived from the aromatic compound having a vinyl group is usually 5 to80 mol % with respect to all constituent units of the copolymer. Such aternary compound has a merit that the use amount of an expensive cyclicolefin can be relatively reduced in its production.

[First Phase Difference Layer]

The first phase difference layer preferably has an optical propertyrepresented by the formula (4), more preferably has an optical propertyrepresented by the formula (4-1). The in-plane phase difference valueRe(550) can be regulated by the same method as the above-describedmethod of regulating the in-plane phase difference value of a phasedifference layer.

100<Re(550)<160  (4)

130<Re(550)<150  (4-1)

Further, the first phase difference layer preferably has opticalproperties represented by the formula (1) and the formula (2). Suchoptical properties can be obtained by the same method as for theabove-described phase difference layer.

Re(450)/Re(550)≦1.00  (1)

1.00≦Re(650)/Re(550)  (2)

The first phase difference layer preferably has a layer A having opticalproperties represented by the formulae (4), (6) and (7) and a layer Bhaving optical properties represented by the formulae (5), (6) and (7).Such optical properties can be obtained by the same method as for theabove-described phase difference layer.

100<Re(550)<160  (4)

200<Re(550)<320  (5)

Re(450)/Re(550)≧1.00  (6)

1.00≧Re(650)/Re(550)  (7)

The layer A is preferably a layer having an optical property representedby the formula (4-1), and the layer B is preferably a layer having anoptical property represented by the formula (5-1).

130<Re(550)<150  (4-1)

265<Re(550)<285  (5-1)

When the optical film of the present invention has a third phasedifference layer, the first phase difference layer preferably hasoptical properties represented by the formula (6) and the formula (7).Such optical properties can be obtained by the same method as for theabove-described phase difference layer.

Re(450)/Re(550)≧1.00  (6)

1.00≧Re(650)/Re(550)  (7)

The first phase difference layer is preferably a coating crystal. Whenthe first phase difference layer is composed of one phase differencelayer and has optical properties represented by the formula (1) and theformula (2), such a phase difference layer is preferably a coating layerformed by polymerizing a polymerizable liquid crystal (A). When thefirst phase difference layer has optical properties represented by theformula (6) and the formula (7), such phase difference layer ispreferably a coating layer formed by polymerizing a polymerizable liquidcrystal (B).

The layer A is preferably a coating layer formed by polymerizing apolymerizable liquid crystal (B). The layer B is preferably a coatinglayer formed by polymerizing a polymerizable liquid crystal (C).

Further, the thickness of the first phase difference layer in thepresent optical film is preferably 1.0 μm to 7.5 μm. When the thicknessof the first phase difference layer is smaller than 1.0 μm, thecompensation effect of the first phase difference layer decreases,consequently, it becomes difficult to suppress light leakage when viewedfrom the front side. When larger than 7.5 μm, the distance of the firstphase difference layer though which light transmits (optical pathlength) becomes larger. As a result, the compensation effect by thephase difference layer relatively decreases, and it becomes difficult tosuppress light leakage. Further, it is preferable that the thickness ofthe first phase difference layer is smaller, also from the standpoint ofthinning.

Though the first phase difference layer can be formed by drawing a film,it is preferable to form the first phase difference layer bypolymerizing a polymerizable liquid crystal since the thickness can bearbitrarily controlled by coating conditions. The thickness of the firstphase difference layer can be determined by measurement by aninterference thickness meter, a laser microscope or a contact-typethickness meter.

The thickness of the layer A is preferably 0.5 μm to 2.5 μm.

The thickness of the layer B is preferably 0.5 μm to 5.0 μm. It is morepreferable that both the layer A and the layer B have a thickness of 2.5μm or less.

The thickness of the layer A and the layer B can be measured by the samemethod as for the first phase difference layer.

[Second Phase Difference Layer]

The second phase difference layer has an optical property represented bythe formula (3).

nx≈ny<nz  (3)

The in-plane phase difference value Re(550) of the second phasedifference layer is usually in the range of 0 to 10 nm, preferably inthe range of 0 to 5 nm. The phase difference value Rth in the thicknessdirection is usually in the range of −10 to −300 nm, preferably in therange of 20 to −200 nm. Such in-plane phase difference value Re(550) andphase difference value Rth in the thickness direction can be regulatedby the same method as for the above-described phase difference layer.

The second phase difference layer is preferably a coating layer formedby polymerizing at least one polymerizable liquid crystal. Morepreferable, it is a coating layer formed by polymerizing a polymerizableliquid crystal (B).

The thickness of the second phase difference layer is 0.2 μm to 2.0 μm,preferably 0.3 μm to 1.0 μm.

When the thickness of the second phase difference layer is 0.2 μm to 2.0μm, light leakage when viewed from an oblique direction can besuppressed. For example, when an organic EL display having a circularpolarization plate composed of the present optical film is visuallyrecognized at a position of an elevation angle of 60° from the frontvertical direction, it is possible to suppress light leakage from anyazimuth direction. When the thickness is smaller than 0.2 μm, lightleakage cannot be suppressed since the compensation effect of direction.When the thickness is smaller than 0.2 μm, light leakage cannot besuppressed since the compensation effect of the second phase differencelayer is too small, and when larger than 2.0 μm, the compensation effectof the second phase difference layer is excessive, and the amount ofpolymerizable conversion varies significantly from the desired amount,resultantly, light leakage is generated.

It is preferable that the second phase difference layer is a layercomposed particularly of a polymerizable liquid crystal since itsoptical property can be arbitrarily controlled by regulating thethickness.

The thickness of the second phase difference layer can be measured bythe same method as for the first phase difference layer. Further, it ispreferable that the thickness of first phase difference layer and thethickness of the second phase difference layer are 2.0 μm or less,respectively.

[Third Phase Difference Layer]

The third phase difference layer has an optical property represented bythe formula (5), preferably has an optical property represented by theformula (5-1). The in-plane phase difference value Re(550) can beregulated by the same method as the above-described method of regulatingthe in-plane phase difference value of a phase difference layer.

200<Re(550)<320  (5)

265<Re(550)<285  (5-1)

The third phase difference layer preferably has optical propertiesrepresented by the formula (6) and the formula (7). Such opticalproperties can be obtained by the same method as for the above-describedphase difference layer.

Re(450)/Re(550)≧1.00  (6)

1.00≧Re(650)/Re(550)  (7)

The third phase difference layer is preferably a coating layer formed bypolymerizing at least one polymerizable liquid crystal. More preferably,it is a coating layer formed by polymerizing a polymerizable liquidcrystal (B) or (C).

When the third phase difference layer is a drawn film, its thickness isusually 300 μm or less, preferably 5 μm or more and 100 μm or less, morepreferably 10 μm or more and 50 μm or less. When the third phasedifference layer is a layer formed by polymerizing a polymerizableliquid crystal, its thickness is usually 10 μm or less, preferably 5 82m or less, more preferably 0.5 μm or more and 5 μm or less. Thethickness of the third phase difference layer can be measured by thesame method as for the first phase difference layer.

<Base Material>

The optical film of the present invention preferably has a basematerial. The base material includes the same materials as describedabove.

The surface of a base material on which an orientation film, a firstphase difference layer, a second phase difference layer and a thirdphase difference layer are formed may be subjected to a surfacetreatment before forming the orientation film or the phase differencelayer. The surface treatment method includes a method of treating thesurface of a base material with corona or plasma under vacuum or underatmospheric pressure, a method of treating the surface of a basematerial with laser, a method of treating the surface of a base materialwith ozone, a method of saponifying the surface of a base material or amethod of treating the surface of a base material with flame, a primertreatment method of coating a coupling agent on the surface of basematerial, a graft polymerization method of allowing a reactive monomeror a polymer having reactivity to adhere to the surface of a basematerial, then, reacting this by irradiation with radiation, plasma orultraviolet, and the like. Of them, the method of treating the surfaceof a base material with corona or plasma under vacuum or underatmospheric pressure is preferable.

The method of treating the surface of a base material with corona orplasma includes,

a method in which, under pressure near atmospheric pressure,a base material is disposed between facing electrodes, corona or plasmais generated and the surface of the base material is treated,a method in which a gas is allowed to flow through between facingelectrodes, the gas is converted into plasma between the electrodes andthe plasma gas is blown onto the base material, and,a method in which glow discharge plasma is generated under low voltagecondition, and the surface of a base material is treated with thegenerated plasma,.

Of them, the method in which, under pressure near atmospheric pressure,a base material is disposed between facing electrodes, corona or plasmais generated and the surface of the base material is treated, or themethod in which a gas is allowed to flow through between facingelectrodes, the gas is converted into plasma between the electrodes andthe plasma gas is blown onto the base material is preferable. Such asurface treatment with corona or plasma is usually carried out by acommercially available surface treatment apparatus.

As the base material, a base material showing small phase difference ispreferable. The base material showing small phase difference includescellulose ester films having no phase difference such as ZEROTAC(registered trademark) (Konica Minolta Opto Products Co., Ltd.), Z TAC(Fujifilm Corporation) and the like. Further, an undrawn cyclic olefinresin base material is also preferable.

Furthermore, the surface of a base material on which an orientationfilm, a first phase difference layer, a second phase difference layerand a third phase difference layer are not formed may be subjected to ahard coat treatment, an antistatic treatment and the like. Additivessuch as an ultraviolet absorber and the like may be contained in a rangenot affecting the performance.

When the thickness of a base material is too small, strength lowers andworkability tends to be poor, therefore, the thickness is usually 5 to300 μm, preferably 10 to 200 μm.

<Polymerizable Liquid Crystal Composition>

The layer formed by polymerizing a polymerizable liquid crystal (phasedifference layer) is usually formed by coating a composition containingat least one polymerizable liquid crystal (hereinafter, referred to aspolymerizable liquid crystal composition in some cases) on a basematerial, an orientation film, a protective film or a phase differencelayer, and polymerizing the polymerizable liquid crystal in theresulting coated film.

The polymerizable liquid crystal composition usually contains a solvent,and more preferable as the solvent is a solvent which can dissolve apolymerizable liquid crystal and is inactive for the polymerizationreaction of the polymerizable liquid crystal.

The solvent includes, specifically, alcohol solvents such as methanol,ethanol, ethylene glycol, isopropyl alcohol, propylene glycol,methylcellosolve, butylcellosolve, propylene glycol monomethyl ether,phenol and the like; ester solvents such as ethyl acetate, butyl acetateand the like; ketone solvents such as acetone, methyl ethyl ketone,cyclopentanone, cyclohexanone, cycloheptanone, methyl amyl ketone,methyl isobutyl ketone, N-methyl-2-pyrrolidinone and the like;nonchlorinated aliphatic hydrocarbon solvents such as pentane, hexane,heptane and the like; nonchlorinated aromatic hydrocarbon solvents suchas toluene, xylene and the nitrile solvents such as acetonitrile and thelike; ether solvents such as propylene glycol monomethyl ether,tetrahydrofuran, dimethoxyethane and the like, and chlorinatedhydrocarbon solvents such as chloroform, chlorobenzene and the like.These other solvents may be used singly or in combination.

The content of a solvent in a polymerizable liquid crystal compositionis preferably 10 parts by mass to 10000 parts by mass, more preferably50 parts by mass to 5000 parts by mass with respect to 100 parts by massof the solid content. The solid content means the sum of components of apolymerizable liquid crystal composition excluding a solvent.

Coating of a polymerizable liquid crystal composition is usually carriedout by known methods such as coating methods such as a spin coatingmethod, an extrusion method, a gravure coating method, a die coatingmethod, a slit coating method, a bar coating method, an applicatormethod and the like, and printing methods such as a flexo method and thelike. After coating a dry coat is formed usually by removing a solventunder conditions wherein a polymerizable liquid crystal contained in theresultant coated film does not polymerize. The drying method includes anatural drying method, a ventilation drying method, heat drying and areduced-pressure drying method.

<Orientation Film>

The orientation film in the present invention has orientationcontrolling force of orienting a polymerizable liquid crystal to adesired direction.

It is preferable that the orientation film has solvent resistance withwhich the film is not dissolved in coating of a polymerizable liquidcrystal composition and has heat resistance in a heat treatment forremoval of a solvent and orientation of a polymerizable liquid crystal.Such an orientation film includes an orientation film containing anorienting polymer, a photo-orientation film, and a groove orientationfilm having irregular patterns and a plurality of grooves formed fororientation on the surface.

The orienting polymer includes polyamides and gelatins having an amidebond in the molecule, polyimides having an imide bond in the moleculeand polyamic acids as hydrolysates thereof, polyvinyl alcohol,alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole,polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acidand polyacrylates. Of them, polyvinyl alcohol is preferable. It is alsopermissible to use two or more orienting polymers in combination.

The orientation film containing an orienting polymer is usually obtainedby coating a composition containing an orienting polymer dissolved in asolvent (hereinafter, referred to as orienting polymer composition insome cases) on a base material and removing the solvent, or coating anorienting polymer composition on a base material, removing the solventand rubbing the composition (rubbing method).

The above-described solvent includes, water, alcohol solvents such asmethanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol,methylcellosolve, butylcellosolve, propylene glycol monomethyl ether andthe like, ester solvents such as ethyl acrylate, butyl acrylate,ethylene glycol methylether acrylate, γ-butyrolactone, propylene glycolmethyl ether acrylate, ethyl lactate and the like, ketone solvents suchas acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methylamyl ketone, methyl isobutyl ketone and the like, aliphatic hydrocarbonsolvents such as pentane, hexane, heptane and the like, aromatichydrocarbon solvents such as toluene, xylene and the like, nitrilesolvents such as acetonitrile and the like, ether solvents such astetrahydrofuran, dimethoxyethane and the like, and chlorinatedhydrocarbon such as chloroform, chlorobenzene and the like. Thesesolvents may be used singly or two or more of them may be used incombination.

The concentration of an orienting polymer in an orienting polymercomposition may be in a range wherein the orienting polymer material canbe dissolved completely in a solvent, and it is preferably 0.1. to 20%,further preferably about 0.1 to 10% in terms of the solid content withrespect to the solution.

As the orienting polymer composition, a commercially availableorientation film material may be used as it is. The commerciallyavailable orientation film material includes SUNEVER (registeredtrademark, manufactured by Nissan Chemical, Industries, Ltd.), OPTOMER(registered trademark, manufactured by JSR Corporation), and the like.

The method of coating an orienting polymer composition on a basematerial includes known methods such as coating methods such as a spincoating method, an extrusion method, a gravure coating method, a diecoating method, a slit coating method, a bar coating method, anapplicator method and the like, printing methods such as a flexo methodand the like. When the present optical film is produced by a continuousproduction method of Roll to Roll mode described later, a gravurecoating method, a die coating method or a printing method such as aflexo method or the like is usually adopted in the coating method.

The method of removing a solvent contained in an orienting polymercomposition includes a natural drying method, ventilation drying method,heat drying and a reduced-pressure drying method, and the like.

To endow an orientation film with orientation controlling rubbing can beconducted (rubbing method) if necessary.

For endowing orientation controlling force by the rubbing method, thereis a method in which a film of an orienting polymer formed on thesurface of a base material by coating an orienting polymer compositionon the base material and annealing this is made to contact with arubbing roll which is rotating and carrying rubbing cloth wound thereon.

To endow an orientation film with orientation controlling force,photo-orientation can be conducted (photo-orientation method) ifnecessary.

The photo-orientation film is obtained usually by coating a compositioncontaining a solvent and a polymer or monomer having a photo-reactivegroup (hereinafter, referred to as “photo-orientation film formingcomposition” in some cases) on a base material, and irradiating thecomposition with light (preferably, polarized UV). The photo-orientationfilm is more preferable since the direction of orientation controllingforce can be controlled arbitrarily by selecting the polarizationdirection of light used for irradiation.

The photo-reactive group denotes a group generating liquid crystalorienting ability by light irradiation. The photo-reactive groupincludes, specifically, groups correlated with photo-reactions acting asan origin of liquid crystal orienting ability such as an isomerizationreaction, a dimerization reaction, a photo-crosslinking reaction, aphoto-decomposition reaction and the like or with induction oforientation of molecules generated by light irradiation. Of them, groupscorrelated with a dimerization reaction or a photo-crosslinking reactionare preferable because of excellent orientation. As the photo-reactivegroup, groups having an unsaturated bond, especially a double bond arepreferable, and groups having at least one selected from the groupconsisting of a carbon-carbon double bond (C═C bond), a carbon-nitrogendouble bond (C═N bond), a nitrogen-nitrogen double bond (N═N bond) and acarbon-oxygen double bond (C═O bond) are particularly preferable.

The photo-reactive group having a C═C bond includes a vinyl group, apolyene group, a stilbene group, a stilbazole group, a stilbazoliumgroup, a chalcone group and a cinnamoyl group. The photo-reactive grouphaving a C═N bond includes groups having a structure of an aromaticSchiff base, an aromatic hydrazone and the like. The photo-reactivegroup having a N═N bond includes an azobenzene group, an azonaphthalenegroup, an aromatic heterocyclic azo group, a bisazo group, a formazangroup, and groups having an azoxybenzene structure. The photo-reactivegroup having a C═O bond includes a benzophenone group, a coumarin group,an anthraquinone group and a maleimide group. These groups may have asubstituent such as an alkyl group, an alkoxy group, an aryl group, anaryloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group,a sulfonic group, a halogenated alkyl group and the like.

Of them, photo-reactive groups correlated with a photo-dimerizationreaction are preferable, and a cinnamoyl group and a chalcone group arepreferable since the polarization irradiance level necessary forphoto-orientation is relatively small and a photo-orientation filmexcellent in thermal stability and temporal stability is easilyobtained. As the polymer having a photo-reactive group, those having acinnamoyl group so that the end of a side chain of the polymer has acinnamic acid structure.

A photo-orientation induction layer can be formed on a base material bycoating a photo-orientation film forming composition on the basematerial. The solvent contained in the composition includes the samesolvents as one contained in the above-described orienting polymercomposition, and can be appropriately selected depending on thesolubility of a polymer or monomer having a photo-reactive group.

The content of a polymer or monomer having a photo-reactive group in aphoto-orientation film forming composition can be appropriately adjusteddepending on the kind of the polymer or monomer and the thickness of theintended photo-orientation film, and is preferably at least 0.2% bymass, more preferably in the range of 0.3 to 10% by mass. Thephoto-orientation film forming composition may contain a photosensitizerand a polymer material such as polyvinyl alcohol, polyimide or the likein a range wherein the property of a photo-orientation film is notremarkably lost.

The method of coating a photo-orientation film forming composition on abase material includes the same methods as the method of coating anorienting polymer composition on a base material. The method of removinga solvent from the coated photo-orientation film forming compositionincludes, for example, the same methods as the method of removing asolvent from an orienting polymer composition.

Irradiation with polarization may be carried out by a mode in which asolvent is removed from a photo-orientation film forming compositioncoated on a base material and the composition is irradiated directlywith polarization UV or a mode in which the base material side isirradiated with polarization and the polarization is allowed totransmit, and the composition is irradiated with the transmittedpolarization. It is particularly preferable that this polarization issubstantially parallel light. The wavelength of polarization used forirradiation is preferably in a range wherein a photo-reactive group of apolymer or monomer having a photo-reactive group can absorb opticalenergy. Specifically, UV (ultraviolet) having a wavelength in the rangeof 250 to 400 nm is particularly preferable. The light source used forthe polarization irradiation includes a xenon lamp, a high pressuremercury lamp, an extra high pressure mercury lamp, a metal halide lamp,ultraviolet laser such as KrF, ArF and the like, and a high pressuremercury lamp, an extra high pressure mercury and a metal halide lamp aremore preferable. These lamps are preferable since they provide highemission intensity of ultraviolet having a wavelength of 313 nm. Bydelivering light from the above-described light source via a suitablepolarizer, irradiation with polarization UV is made possible. As thepolarizer, use is made of a polarization filter, a polarization prismsuch as Glan Thompson, Glan Taylor and the like, and a wire grid typepolarizer.

If masking is performed in conducting rubbing or polarizationirradiation, several regions having different liquid crystal orientationdirections (pattern) can also be formed.

The groove orientation film is a film in which liquid crystalorientation is obtained by irregular patterns or a plurality of grooveson the surface of the film. H. V. Kennel et al. report a fact that ifliquid crystal molecules are placed on a base material having aplurality of linear grooves arranged at regular intervals, liquidcrystal molecules are oriented to a direction along the grooves(Physical Review A24 (5): p. 2713, 1981).

Specific examples for obtaining a groove orientation film includes amethod in which the surface of a photo-sensitive polyimide is exposedvia an exposure mask having periodically patterned slits, then,development and rinse treatments are conducted to remove unnecessarypolyimide films, thereby forming irregular patterns, a method in whichan UV curable resin layer is formed on a plate-shaped master havinggrooves on the surface, and the resin layer is transferred onto a basematerial film before curing, a method in which a base material filmhaving an UV curable resin layer formed thereon is conveyed, and aroll-shaped master having a plurality of grooves is pressed to thesurface of the UV curable resin layer to form irregularity beforeperforming curing, and the like, and methods described in JP-A No.6-34976 and No. 2011-242743 can be used.

Of the above-described methods, the method of pressing a roll-shapedmaster having a plurality of grooves to the surface of an UV curableresin layer to form irregularity before performing curing is preferable.As the roll-shaped master, stainless (SUS) steel can be used from thestandpoint of durability.

As the UV curable resin, a polymer of a mono-functional acrylate, apolymer of a poly-functional acrylate or a polymer of a mixture of themcan be used.

The mono-functional acrylate is a compound having in the molecule onegroup (hereinafter, referred to as (meth)acryloyloxy group in somecases) selected from the group consisting of an acryloyloxy group(CH₂═CH—COO—) and a methacryloyloxy group (CH₂═C(CH₃)—COO—).

The mono-functional acrylate having one (meth)acryloyloxy group includesalkyl (meth)benzophenones having 4 to 16 carbon atoms, β-carboxyalkyl(meth)acrylates having 2 to 14 carbon atoms, alkylated phenyl(meth)acrylates having 2 to 14 carbon atoms, methoxypolyethylene glycol(meth)acrylate, phenoxy polyethylene glycol (meth)acrylate and isobonyl(meth)acrylate, and the like.

The poly-functional acrylate is usually a compound having in themolecule two to six (meth)acryloyloxy groups.

As the bi-functional acrylate having two (meth)acryloyloxy groups,1,3-butanediol di(meth)acrylate; 1,3-butanediol (meth)acrylate;1,6-hexanediol di(meth)acrylate; ethylene glycol di(meth)acrylate;diethylene glycol di(meth)acrylate; neopentyl glycol di(meth)acrylate;triethylene glycol di(meth)acrylate; tetraethylene glycoldi(meth)acrylate; polyethylene glycol diacrylate; bis(acryloyloxyethyl)ether of bisphenol A; ethoxylated bisphenol A di(meth)acrylate;propoxylated neopentyl glycol di(meth)acrylate; ethoxylated neopentylglycol di(meth)acrylate and 3-methylpentanediol di(meth)acrylate, andthe like are exemplified.

The poly-functional acrylate having three to six (meth)acryloyloxygroups includes,

trimethylolpropane tri(meth)acrylate; pentaerythritol tri(meth)acrylate;tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate; ethoxylatedtrimethylolpropane tri(meth)acrylate; propoxylated trimethylolpropanetri(meth)acrylate; pentaerythritol tetra(meth)acrylate;dipentaerythritol penta(meth)acrylate; dipentaerythritolhexa(meth)acrylate; tripentaerythritol tetra(meth)acrylate;tripentaerythritol penta(meth)acrylate; tripentaerythritolhexa(meth)acrylate; tripentaerythritol hepta(meth)acrylate;tripentaerythritol octa(meth)acrylate;

a reaction product of pentaerythritol tri(meth)acrylate with an acidanhydride; a reaction product of dipentaerythritol penta(meth)acrylatewith an acid anhydride; a reaction product of tripentaerythritolhepta(meth)acrylate with an acid anhydride;

caprolactone-modified trimethylolpropane tri(meth)acrylate;caprolactone-modified pentaerythritol tri(meth)acrylate;caprolactone-modified tris(2-hydroxyethyl) isocyanuratetri(meth)acrylate; caprolactone-modified pentaerythritoltetra(meth)acrylate; caprolactone-modified dipentaerythritolpenta(meth)acrylate; caprolactone-modified dipentaerythritolhexa(meth)acrylate; caprolactone-modified tripentaerythritoltetra(meth)acrylate; caprolactone-modified tripentaerythritolpenta(meth)acrylate; caprolactone-modified tripentaerythritolhexa(meth)acrylate; caprolactone-modified tripentaerythritolhepta(meth)acrylate; caprolactone-modified tripentaerythritolocta(meth)acrylate; a reaction product of caprolactone-modifiedpentaerythritol tri(meth)carbazole with an acid acrylate; a reactionproduct of caprolactone-modified dipentaerythritol penta(meth)acrylatewith an acid anhydride, and a reaction product of caprolactone-modifiedtripentaerythritol hepta(meth)carbazole with an acid anhydride, and thelike. In specific examples of the poly-functional acrylate listed here,the (meth)acrylate denotes acrylate or methacrylate. Thecaprolactone-modified means that a ring-opened body of caprolactone or aring open polymerized body thereof is introduced between analcohol-derived portion and a (meth)acryloyloxy group of a(meth)acrylate compound.

As the poly-functional acrylate, commercially available products canalso be used.

Such commercially available products include A-DOD-N, A-HD-N, A-NOD-N,APG-100, APG-200, APG-400, A-GLY-9E, A-GLY-20E, A-TMM-3, A-TMPT, AD-TMP,TTM-35E, A-TMMT, A-9550, A-DPH, HD-N, NON-N, NPG, TMPT (manufactured byShin Nakamura Chemical Co., Ltd.); “ARONIX M-220”, same brand “M-325”,same brand “M-240”, same brand “M-270”, same brand “M-309”, same brand“M-310”, same brand “M-321”, same brand “M-350”, same brand “M-360”,same brand “M-305”, same brand “M-306”, same brand “M-450”, same brand“M-451”, same brand “M-408”, same brand “M-400”, same brand “M-402”,same brand “M-403”, same brand “M-404”, same brand “M-405”, same brand“M-406” manufactured by Toagosei Cc., Ltd.), “EBECRYL11”, same brand“145”, same brand “150”, same brand “40”, same brand “140”, same brand“180”, DPGDA, HDDA, TPGDA, HPNDA, PETIA, PETRA, TMPTA, TMPEOTA, DPHA,EBECRYL series (manufactured by Daicel-Cytec Company, Ltd.), and thelike.

Regarding irregularity of a groove orientation film, the width of aconvex portion is preferably 0.05 to 5 μm, the width of a concaveportion is preferably 0.1 to 5 μm, the depth of irregularity is 2 μm orless, preferably 0.01 to 1 μm or less. Within this range, liquid crystalorientation revealing little disordered orientation can be obtained.

The thickness of an orientation film is usually in the range of 10 nm to10000 nm, preferably in the range of 10 nm to 1000 nm, more preferably500 nm or less, further preferably in the range of 10 nm to 500 nm.

Liquid crystal orientation of a polymerizable liquid crystal isregulated by the nature of an orientation film and a polymerizableliquid crystal. For example, if an orientation film is a materialmanifesting horizontal orientation controlling force as orientationcontrolling force, a polymerizable liquid crystal can form horizontalorientation or hybrid orientation, while if it is a material manifestingvertical orientation controlling force, a polymerizable liquid crystalcan form vertical orientation or inclined orientation.

When an orientation film is formed of an orienting polymer, orientationcontrolling force can be arbitrarily controlled by surface state andrubbing condition, while when an orientation film is formed of aphoto-orienting polymer, orientation controlling force can bearbitrarily controlled by polarization irradiation condition and thelike. Liquid crystal orientation can also be controlled by selectingphysical properties such as surface tension, liquid crystallinity andthe like of a polymerizable liquid crystal.

Polymerization of a polymerizable liquid crystal can be conducted by aknown method of polymerizing a compound having a polymerizablefunctional group. heat polymerization and photo-polymerization arespecifically mentioned, and photo-polymerization is preferable from thestandpoint of easiness of polymerization. when a polymerizable liquidcrystal is polymerized by photo-polymerization, it is preferable that apolymerizable liquid crystal composition containing aphotopolymerization initiator is coated and dried to obtain a dry coat,and a polymerizable liquid crystal in the coat is converted into liquidcrystal phase state, then, photo-polymerization is performed whilekeeping the liquid crystal state.

Photo-polymerization carried out usually by irradiating a dry coat withlight. Light used for irradiation is appropriately selected depending onthe kind of a photopolymerization initiator contained in a dry coat, thekind of a polymerizable liquid crystal (particularly, the kind of aphotopolymerizable group in a polymerizable liquid crystal) and itsamount, and includes, specifically, light selected from the groupconsisting of visible light, ultraviolet light and laser light, and anactive electron beam. Of them, ultraviolet light is preferable sinceprogress of a polymerization reaction can be easily controlled andapparatuses widely used in the art as a photopolymerization apparatuscan be used, and it is preferable to select the kind of a polymerizableliquid crystal and a photopolymerization initiator so thatphotopolymerization can occur with ultraviolet light. It is alsopossible to control the polymerization temperature by irradiating a drycoat with light while cooling with a suitable cooling means, inpolymerization. When polymerization of a polymerizable liquid crystal iscarried out at lower temperature by adoption of such a cooling means, aphase difference layer can be suitably formed, even if a base materialof relatively low heat resistance is used. A patterned phase differencelayer can also be obtained, by conducting masking or development inphotopolymerization).

The polymerizable liquid crystal composition may contain a reactiveadditive.

As the reactive additive, those having a carbon-carbon unsaturated bondand an active hydrogen reactive group in the molecule are preferable.“Active hydrogen reactive group” herein referred to denotes a groupshowing reactivity with a group having active hydrogen such as acarboxyl group (—COOH), a hydroxyl group (—OH), an amino group (—NH₂)and the like, and a glycidyl group, an oxazoline group, a carbodiimidegroup, an aziridine group, an imide group, an isocyanate group, athioisocyanate group, a maleic anhydride group and the like are typicalexamples thereof. The number of each of a carbon-carbon unsaturated bondand an active hydrogen reactive group in a reactive additive is usually1 to 20, preferably 1 to 10.

It is preferable that at least two active hydrogen reactive groups arepresent in a reactive additive, and in this case, a plurality of activehydrogen reactive groups may be the same or different.

The carbon-carbon unsaturated bond in a reactive additive may be acarbon-carbon double bond or a carbon-carbon triple bond, or acombination thereof, and preferable is carbon-carbon double bond.Particularly, it is preferable for a reactive additive to contain acarbon-carbon unsaturated bond in the form of a vinyl group and/or a(meth)acryl group. Further, it is preferable that the active hydrogenreactive group is at least one selected from the group consisting of anepoxy group, a glycidyl group and an isocyanate group, and reactiveadditives having an acryl group and an isocyanate group are particularlypreferable.

Specific examples of the reactive additive include compounds having a(meth)acryl group and an epoxy group such as methacryloxy glycidylether, acryloxy glycidyl ether and the like; compounds having a(meth)acryl group and an oxetane group such as oxetane acrylate, oxetanemethacrylate and the like; compounds having a (meth)acryl group and alactone group such as lactone acrylate, lactone methacrylate and thelike; compounds having a vinyl group and an oxazoline group such asvinyloxazoline, isopropenyloxazoline and the like; oligomers ofcompounds having a (meth)acryl group and an isocyanate group such asisocyanatomethyl acrylate, isocyanatomethyl methacrylate,2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate and thelike. Further listed are compounds having a vinyl group or vinylenegroup and an acid anhydride such as methacrylic anhydride, acrylicanhydride, maleic anhydride, vinylmaleic anhydride and the like. Ofthem, methacryloxy glicidyl ether, acryloxy glycidyl ether,isocyanatomethyl acrylate, isocyanatomethyl methacrylate,vinyloxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethylmethacrylate and the above-described oligomers are preferable,isocyanatomethyl acrylate, 2-isocyanatoethyl acrylate and theabove-described oligomers are particularly preferable.

Specifically, compounds represented by the following formula (Y) arepreferable.

[In the formula (Y),

n represents an integer of 1 to 10, R^(1′) represents a di-valentaliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms, ora di-valent aromatic hydrocarbon group having 5 to 20 carbon atoms. Oneof two R^(2′) in each repeating unit is —NH— and the other is a grouprepresented by >N—C(═O)—R^(3′). R^(3′) represents a hydroxyl group or agroup having a carbon-carbon unsaturated bond.

At least one of R^(3′) in the formula (Y) is a group having acarbon-carbon unsaturated bond.]

Of reactive additives represented by the above-described formula (Y),compounds represented by the following formula (YY) (hereinafter,referred to as compound (YY) in some cases) are particularly preferable(n represents the same meaning as described above).

As the compound (YY), commercially available products can be used asthey are or, if necessary, purified before use. The commerciallyavailable product includes, for example, Laromer (registered trademark)LR-9000 (manufactured by BASF).

When the polymerizable liquid crystal composition contains a reactiveadditive, its content is usually 0.1 part by mass to 30 parts by mass,preferably 0.1 part by mass to 5 parts by mass with respect to 100 partsby mass of a polymerizable liquid crystal.

It is preferable that the polymerizable liquid crystal compositioncontains at least one leveling agent. The leveling agent has a functionof adjusting flowability of a polymerizable liquid crystal compositionand making a coated film obtained by coating a polymerizable liquidcrystal composition more even, and includes, specifically, surfactants.As the leveling agent, at least one selected from the group consistingof leveling agents containing a polyacrylate compound as the maincomponent and leveling agents containing a fluorine atom-containingcompound as the main component is preferable.

The leveling agent containing a polyacrylate compound as the maincomponent includes “BYK-350”, “BYK-352”, “BYK-353”, “BYK-354”,“BYK-355”, “BYK-358N”, “BYK-361N”, “BYK-380”, “BYK-381” AND “BYK-392”[BYK Chemie].

The leveling agent containing a fluorine atom-containing compound as themain component includes “MEGAFAC (registered trademark) R-08”, samebrand “R-30”, same brand “R-90”, same brand “F-410”, same brand “F-411”,same brand “F-443”, same brand “F-445”, same brand “F-470”, same brand“F-471”, same brand “F-477”, same brand “F-479”, same brand “F-482” andsame brand “F-483” [DIC Corporation ]; “Surflon (registered trademark)S-381”, same brand “S-382”, same brand “S-383”, same brand “S-393”, samebrand “S-382”, same brand “SC-105”, “KH-40” and “SA-100” [AGC SeimiChemical Co., Ltd.]; “E1830”, “E5844” [Daikin Fine Chemical Laboratory,Ltd.]; “EFTOP EF301”, “EFTOP EF303”, “EFTOP EF351”and “EFTOP EF352”[Mitsubishi Materials Electronic Chemicals Co., Ltd.].

When the polymerizable liquid crystal composition contains a levelingagent, its content is preferably 0.01 part by mass or more and 5 partsby mass or less, more preferably 0.05 parts by mass or more and 5 partsby mass or less, further preferably 0.05 parts by mass or more and 3parts by mass or less with respect to 100 parts by mass of apolymerizable liquid crystal. When the content of a leveling agent is inthe above-described range, horizontal orientation of a polymerizableliquid crystal is easy and the resultant polarization layer tends to bemore even. When the content of a leveling agent with respect to apolymerizable liquid crystal is in the above-described range, there is atendency that unevenness is scarcely generated in the resultant phasedifference layer.

It is preferable that the polymerizable liquid crystal compositioncontains at least one polymerization initiator. The polymerizationinitiator is a compound capable of initiating a polymerization reactionof a polymerizable liquid crystal, and a photopolymerization initiatoris preferable since a polymerization reaction can be initiated at lowertemperature condition. Specifically, photopolymerization initiatorscapable of generating an active radical or an acid by the action oflight are mentioned, and of them, photopolymerization initiatorsgenerating a radical by the action of light are preferable.

The polymerization initiator includes a benzoin compound, a benzophenonecompound, an alkylphenone compound, an acylphosphine oxide compound, atriazine compound, an iodonium salt and a sulfonium salt.

The benzoin compound includes benzoin, benzoin methyl ether, benzoinethyl ether, benzoin isopropyl ether and benzoin isobutyl ether.

The benzophenone compound includes benzophenone, methylo-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyl diphenylsulfide, 3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone and2,4,6-trimethylbenzophenone.

The alkylphenone compound includes oligomers of diethoxyacetophenone,2-methyl-2-morphonino-1-(4-methylthiophenyl)propan-1-one,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one,2-hydroxy-2-methyl-1-phenylpropan-1-one,1,2-diphenyl-2,2-dimethoxyethan-1-one,2-hydroxy-2-methyl-1[4-(2-hydroxyethoxy)phenyl]propan-1-one,1-hydroxycyclohexyl phenyl ketone and2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propan-1-one.

The acylphosphine oxide compound includes 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl) phenylphosphineoxide.

The triazine compound includes2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine,2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine,2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine,2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl]-1,3,5-triazine,2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine,2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazineand2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine.

As the polymerization initiator, commercially available products can beused. The commercially available polymerization initiator includes“Irgacure (registered trademark) 907”, “Irgacure (registered trademark)184”, “Irgacure (registered trademark) 651”, “Irgacure (registeredtrademark) 819”, “Irgacure (registered trademark) 250”, “Irgacure(registered trademark) 369” (Ciba Japan K.K.); “SEIKUOL (registeredtrademark) BZ”, “SEIKUOL (registered trademark) Z”, “SEIKUOL (registeredtrademark )BEE” (Seiko Chemical Co., Ltd.); “Kayacure (registeredtrademark) BP100” (Nippon Kayaku Co., Ltd.); “Kayacure (registeredtrademark) UVI-6992” (The Dow Chemical Company); “ADEKA OPTOMERSP-152”,“ADEKA OPTOMERSP-170” (ADEKA Corporation); “TAZ-A”, “TAZ-PP” (NipponSiebel Hegner Ltd.); and “TAZ-104” (Sanwa Chemical Co., Ltd.).

When the polymerizable liquid crystal composition contains apolymerization initiator, its content can be appropriately adjusteddepending on the kind of a polymerizable liquid crystal contained in thecomposition and its amount, and is preferably 0.1 to 30 parts by mass,more preferably 0.5 to 10 parts by mass, further preferably 0.5 to 8parts by mass with respect to 100 parts by mass of a polymerizableliquid crystal. When the content of a polymerization initiator is inthis range, the composition can be polymerized without disturbingorientation of a polymerizable liquid crystal.

When the polymerizable liquid crystal composition contains aphotopolymerization initiator, the composition may further contain aphotosensitizer. The photosensitizer includes xanthone compounds such asxanthone, thioxanthone and the like (for example,2,4-diethylthioxanthone, 2-isopropylthioxanthone, and the like);anthracene compounds such as anthracene, alkoxy group-containinganthracene (for example, dibutoxyanthracene, etc.) and the like;phenothiazine and rubrene.

When the polymerizable liquid crystal composition contains aphotopolymerization initiator and a photosensitizer, a polymerizationreaction of a polymerizable liquid crystal contained in the compositioncan be more promoted. The use amount of a photosensitizer can beappropriately adjusted depending on the kind of a photopolymerizationinitiator and a polymerizable liquid crystal and its amount, and ispreferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts bymass, further preferably 0.5 to 2 parts by mass with respect to 100parts by mass of a polymerizable liquid crystal.

To progress a polymerization reaction of a polymerizable liquid crystalmore stably, the polymerizable liquid crystal composition may contain asuitable amount of a polymerization inhibitor, and by this, the degreeof progress of a polymerization reaction of a polymerizable liquidcrystal can be easily controlled.

The polymerization inhibitor includes radical scavengers such ashydroquinone, alkoxy group-containing hydroquinone, alkoxygroup-containing catechol (for example, butylcatechol, etc.),pyrogallol, 2,2,6,6-tetramethyl-1-piperidinyloxy radical and the like;thiophenols; β-naphthylamines and β-naphthols.

When the polymerizable liquid crystal composition contains apolymerization inhibitor, its content can be appropriately adjusteddepending on the kind of a polymerizable liquid crystal and its amount,and the use amount of a photosensitizer, and the like, and is preferably0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass,further preferably 0.5 to 8 parts by mass with respect to 100 parts bymass of a polymerizable liquid crystal. When the content of apolymerization inhibitor is in this range, the composition can bepolymerized without disturbing orientation of a polymerizable liquidcrystal.

When the present optical film is produced, the order of forming a firstphase difference layer, a second phase difference layer and a thirdphase difference layer is arbitrary. Also the order of forming a layer Aand a layer B in a first phase difference layer is arbitrary.

It is permissible that a layer A is formed via or not via an orientationfilm on a base material, a layer B is formed via or not via anorientation film on the layer A, and a second phase difference layer isformed via or not via an orientation film on the layer B.

It is permissible that a layer B is formed via or not via an orientationfilm on a base material, a layer A is formed via or not via anorientation film on the layer B, and a second phase difference layer isformed via or not via an orientation film on the layer A.

It is permissible that a second phase difference layer is formed via ornot via an orientation film on a base material, a layer A is formed viaor not via an orientation film on the second phase difference layer, anda layer B is formed via or not via an orientation film on the layer A.

It is permissible that a second phase difference layer is formed via ornot via an orientation film on a base material, a layer B is formed viaor not via an orientation film on the second phase difference layer, anda layer A is formed via or not via an orientation film on the layer B.

It is permissible that a layer A is formed via or not via an orientationfilm on one surface of a base material, a layer B is formed via or notvia an orientation film an the layer A, and a second phase differencelayer is formed via or not via an orientation film on the other surfaceof a base material.

It is permissible that a layer B is formed via or not via an orientationfilm on one surface of a base material, a layer A is formed via or notvia an orientation film an the layer B, and a second phase differencelayer is formed via or not via an orientation film on the other surfaceof a base material.

When a layer B is formed via or not via an orientation film or a layer Aor when a layer A is formed via or not via an orientation film on alayer B, a protective layer may be present between the layer A and thelayer B. When a layer A is formed via or nor via an orientation film ona second phase difference layer, when a layer A is formed via or not viaan orientation film on a second phase difference layer, when a secondphase difference layer is formed via or not via an orientation film on alayer A or when a second phase difference layer is formed via or not viaan orientation film on a layer B, a protective layer may be presentbetween the second phase difference layer and the layer A or the layerB.

It is permissible that a first phase difference layer is formed via ornot via an orientation film on a base material, a second phasedifference layer is formed via or not via an orientation film on thefirst phase difference layer, and a third phase difference layer isformed via or not via an orientation film on the second phase differencelayer.

It is permissible that a third phase difference layer is formed via ornot via an orientation film on a base material, a second phasedifference layer is formed via or not via an orientation film on thethird phase difference layer, and is first phase difference layer isformed via or not via an orientation film on the second phase differencelayer.

It is permissible that a first phase difference layer is formed via ornot via an orientation film on one surface of a base material, a secondphase difference layer is formed via or nor via an orientation film onthe first phase difference layer, and a third phase difference layer isformed via or not via an orientation film on the other surface of a basematerial.

It is permissible that a second phase difference layer is formed via ornot via an orientation film on one surface of a base material, a firstphase difference layer is formed via or not via an orientation film onthe second phase difference layer, and a third phase difference layer isformed via or not via an orientation film on the other surface of a basematerial.

It is permissible that a third phase difference layer is formed via ornot via an orientation film on one surface of a base material, a secondphase difference layer is formed via or not is an orientation film onthe third phase difference layer, and a first phase difference layer isformed via or not via an orientation film on the other surface of a basematerial.

It is permissible that a second phase difference layer is formed via ornot via an orientation film on one surface of a base material, a thirdphase difference layer is formed via or not via an orientation film onthe second phase difference and a first phase difference layer is formedvia or not via an orientation film on the other surface of a basematerial.

It is permissible that a fist phase difference is formed via or not viaan orientation film on a base material, and a second phase differencelayer is formed via or not via an orientation film on the first phasedifference layer.

It is permissible that a second phase difference layer is formed via ornot via an orientation film on one surface of a base material, and afirst phase difference layer is formed via or not via an orientationfilm on the second phase difference layer.

It is permissible that a second phase difference layer is formed via ornot via an orientation film on one surface of a base material, and afirst phase, difference layer is formed via or not via an orientationfilm on the other surface of a base material.

When a second phase difference layer is formed via or not via anorientation film on a first phase difference layer or when a first phasedifference layer is formed via or not via an orientation film on asecond phase difference layer, a protective layer may be present betweenthe first phase difference layer and the second phase difference layer.When a third phase difference layer is formed via or not via anorientation film on a second phase difference layer or when a secondphase difference layer is formed via or not via an orientation film on athird phase difference layer, a protective layer may be present betweenthe second phase difference layer and the third phase difference layer.

<Protective Layer>

It is preferable that the protective layer is usually formed of aprotective layer forming composition containing a solvent and awater-soluble polymer such as acrylic oligomers or polymers composed ofpoly-functional acrylate (methacrylate), urethane acrylate, polyesteracrylate, epoxy acrylate and the like; polyvinyl alcohol, ethylene-vinylalcohol copolymer, polyvinylpyrrolidone, starches, methylcellulose,carboxymethylcellulose, sodium alginate and the like.

The solvent contained in a protective layer forming composition includesthe same solvents as described above, and of them, at least one solventselected from the group consisting of water, alcohol solvents and ethersolvents is preferable since a layer forming a protective layer is notdissolved therein. The alcohol solvent includes methanol, ethanol,butanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethyleneglycolmethyl ether, ethylene glycolbutyl ether and propylene glycolmonomethyl ether. The ether includes ethylene glycol monomethyl etheracetate and propylene glycol monomethyl ether acetate. Of them, ethanol,isopropyl alcohol, propylene glycol monomethyl ether and propyleneglycol monomethyl ether acetate are preferable.

The thickness of the protective layer is usually 20 μm or less. Thethickness of the protective layer is preferably 0.5 μm or more and 10 μmor less, more preferably 1 μm or more and 5 μm or less. The thickness ofthe protective layer can be determined usually by measurement with aninterference thickness meter, a laser microscope or a contact-typethickness meter.

Next, the method of continuously producing the present optical film willbe illustrated. Such suitable methods for continuously producing thepresent optical film include a method according to the Roll to Rollmode. A method of producing a phase difference layer formed bypolymerizing a polymerizable liquid crystal will be described here,however, a phase difference layer composed of a drawn film may be usedinstead phase difference layer formed by polymerizing a polymerizableliquid crystal, and in this case, “polymerizable liquid crystalcomposition is coated” in the following production step may be replacedby “drawn film is laminated”.

Production methods having typical constitutions are exemplified below,and other constitutions may be carried out according to the followingproduction methods.

In certain methods,

-   (1) a step of preparing a roll carrying a base material wound on a    winding core,-   (2) a step of continuously delivering the base material from the    roll,-   (3) a step of continuously forming an orientation film on the base    material,-   (4) a step of coating a polymerizable liquid crystal composition on    the orientation film to continuously form a first phase difference    layer,-   (5) a step of continuously forming a protective layer on the first    phase difference layer obtained in the above-described step (4),-   (6) a step of continuously forming an orientation film on the    protective layer obtained in the above-described step (5),-   (7) a step of coating a polymerizable liquid crystal composition on    the orientation film obtained in the above-described step (6) to    continuously form a second phase difference layer,-   (8) a step of winding the optical film obtained continuously on a    second winding core to obtain a second roll are conducted in series.    The steps (3), (5) and (6) may be omitted if necessary, and in this    case, “on the orientation film” in the step (4) is replaced by “on    the base material”, “the protective layer obtained in the    above-described step (5)” in the step (6) is replaced by “the first    phase difference layer”, and “the orientation film obtained in the    above-described step (6)” in the step (7) is replaced by “the first    phase difference layer” or “the protective layer obtained in the    above-described step (5)”. For suppressing wrinkle and curl in    conveyance, a protective film may be pasted in conveying a film in    each step.

Further,

-   (1a) a step of preparing a roll carrying a base material wound on a    winding core,-   (2a) a step of continuously delivering the base material from the    roll,-   (3a) step of continuously forming an orientation film on the base    material,-   4a) a step of coating a polymerizable liquid crystal composition on    the orientation film to continuously form a second phase difference    layer,-   (5a) a step of continuously forming a protective layer on the second    phase difference layer obtained in the above-described step (4a),-   (6a) a step of continuously forming an orientation film on the    protective layer obtained in the above-described step (5a),-   (7a) a step of coating a polymerizable liquid crystal composition on    the orientation film obtained in the above-described step (6a) to    continuously form a first phase difference layer,-   (8a) a step of winding the optical film obtained continuously on a    second winding core to obtain a second roll are conducted in series    in certain methods. The steps (3a), (5a) and (6a) may be omitted if    necessary, and in this case, “on the orientation film” in the step    (4a) is replaced by “on the base material”, “the protective layer    obtained in the above-described step (5a)” in the step (6a) is    replaced by “the second phase difference layer”, and “the    orientation film obtained in the above-described step (6a)” in the    step (7a) is replaced by “the second phase difference layer” or “the    protective layer obtained in the above-described step (5a)”. For    suppressing wrinkle and curl in conveyance, a protective film may be    pasted in conveying a film in each step.

Further,

-   (1b) a step of preparing a roll carrying a base material wound on a    winding core,-   (2b) a step of continuously delivering the base material from the    roll,-   (3b) a step of continuously forming an orientation film on the base    material,-   (4b) step of coating a polymerizable liquid crystal composition on    the orientation film to continuously form a first phase difference    layer,-   (5b) a step of continuously forming an orientation film on the    surface of a base material opposite to the first phase difference    layer obtained in the above-described step (4b),-   (6b) a step of coating a polymerizable liquid crystal composition on    the orientation film obtained in the above-described step (5b) to    continuously form a second phase difference layer,-   (7b) a step of winding the optical film obtained continuously on a    second winding core to obtain a second roll are conducted in series    in certain methods. The steps (3b) and (5b) may be omitted if    necessary, and in this case, “on the orientation film” in the step    (4b) is replaced by “on the base material”, “on the orientation film    obtained in the above-described step (5b)” in the step (6b) is    replaced by “the surface of a base material opposite to the first    phase difference layer obtained in the above-described step (4b)”.    For suppressing wrinkle and curl in conveyance, a protective film    may be pasted in conveying a film in each step.

Further,

-   (1c) step of preparing a roll carrying a transparent base material    wound on a winding core,-   (2c) a step of continuously delivering the transparent base material    from the roll,-   (3c) a step of continuously forming an orientation film on the    transparent base material,-   (4c) a step of coating a polymerizable crystal composition on the    orientation film to continuously form a second phase difference    layer,-   (5c) a step of continuously forming an orientation film on the    surface of a base material opposite to the second phase difference    layer obtained in the above-described step (4c),-   (6c) a step of coating a polymerizable liquid crystal composition on    the orientation film obtained in the above-described step (5c) to    continuously form a first phase difference layer,-   (7c) a step of winding the optical film obtained continuously on a    second winding core to obtain a second roll are conducted in series    in certain methods. The steps (3c) and (5c) may be omitted if    necessary, and in this case, “on the orientation film” in the step    (4c) is replaced by “on the base material”, and “on the orientation    film obtained in the above-described step (5c)” in the step (6c) is    replaced by “the surface of a base material opposite to the second    phase difference layer obtained in the above-described step (4c)”.    For suppressing wrinkle and curl in conveyance, a protective film    may be pasted in conveying a film in each step.

Further,

-   (1d) a step of preparing a roll carrying a base material wound on a    winding core,-   (2d) a step of continuously delivering the base material from the    roll,-   (3d) a step of continuously forming an orientation film on the base    material,-   4d) a step of coating a polymerizable liquid crystal composition on    the orientation film to continuously form a layer A,-   (5d) a step of continuously forming a protective layer on the layer    A obtained in the above-described step (4d),-   (6d) a step of continuously forming an orientation film on the    protective layer obtained in the above-described step (5d),-   (7d) a step of coating a polymerizable liquid crystal composition on    the orientation film obtained in the above-described step (6d) to    continuously form a layer B,-   (8d) a step of continuously forming a protective layer on the layer    B obtained in the above-described step (7d),-   (9d) a step of continuously forming an orientation film on the    protective layer obtained in the above-described step (8d),-   (10d) a step of coating a polymerizable liquid crystal composition    on the orientation film obtained in the above-described step (9d) to    continuously form a second phase difference layer,-   (11d) a step of winding the optical film obtained continuously on a    second winding core to obtain a second, roll are conducted in series    in certain methods. The steps (3d), (5d), (6d), (8d) and (9d) may be    omitted if necessary, and in this case, “on the orientation film” in    the step (4d) is replaced by “on the base material”, “the protective    layer obtained in the above-described step (5d)” in the step (6d) is    replaced by “the layer A”, “the orientation film obtained by the    above-described step (6d)” in the step (7d) is replaced by “the    layer A” or “the protective layer obtained in the above-described    step (5d)”, “the protective layer obtained in the above-described    step (8d)” in the step (9d) is replaced by “the layer B”, “the    orientation film obtained in the above-described step (9d)” in the    step (10d) replaced by “the layer B” or “the protective layer    obtained in the above-described step (9d)”. For suppressing wrinkle    and curl in conveyance, a protective film may be pasted in conveying    a film in each step.

Further,

-   (1e) a step of preparing a roll carrying a base material wound on a    winding core,-   (2e) a step of continuously delivering the base material from the    roll,-   (3e) a step of continuously forming an orientation film on the base    material,-   (4e) a step of coating a polymerizable liquid crystal composition on    the orientation film to continuously form a first phase difference    layer,-   (5e) a step of continuously forming a protective layer on the first    phase difference layer obtained in the above-described step (4e),-   (6e) a step of continuously forming an orientation film on the    protective layer obtained in the above-described step (5e),-   (7e) a step of coating a polymerizable liquid crystal composition on    the orientation film obtained in the above-described step (6e) to    continuously form a second phase difference layer,-   (8e) a step of continuously forming an orientation film on the    surface of a base material opposite to the first phase difference    layer obtained in the above-described step (4e),-   (9e) a step of coating a polymerizable liquid crystal composition on    the orientation film obtained in the above-described step (8e) to    continuously form a third phase difference layer,-   (10e) a step of winding the optical film obtained continuously on a    second winding core to obtain a second roll are conducted in series    in certain methods.    The steps (3e), (5e) and (8e) may be omitted if necessary, and in    this case,    “on the orientation film” in the step (4e) a replaced by “on the    base material”,    “the protective layer obtained in the above-described step (5e)” in    the step (6e) is replaced by “the first phase difference layer    obtained in the above-described step (4e)”,    and “on the orientation film obtained in the above-described step    (8e)” in the step (9e) is replaced by “the surface of a base    material opposite to the first phase difference layer obtained in    the above-described step (4e)”. For suppressing wrinkle and curl in    conveyance, a protective film may be pasted in conveying a film in    each step. For stressing wrinkle and curl in conveyance, a    protective film may be pasted in conveying a film in each step.

FIG. 1 shows a schematic view of the present optical film. FIG. 1( b)shows the present optical film 100 having a base material, a first phasedifference layer and a second phase difference layer laminated in thisorder. FIG. 1( c) shows the present optical film 100 having a basematerial, a second phase difference layer and a first phase differencelayer laminated in this order. FIG. 1( d) shows the present optical film100 having a first phase difference layer, a base material and a secondphase difference layer laminated in this order.

A base material can be removed from these present optical films toobtain the present optical films having no base material. When the firstphase difference layer is a drawn film, a second phase difference layeras a coating layer can be formed on the surface of the drawn film toproduce the present optical film, and when the second phase differencelayer is a drawn film, a first phase difference layer as a coating layercan be formed on the surface of the drawn film to produce the presentoptical film. A schematic view of the present optical film having nobase material is shown in FIG. 1( a).

The present optical film can also be produced by pasting a base materialhaving a first phase difference layer and a base material having asecond phase difference layer. As specific examples, FIG. 1( e), FIG. 1(f) and FIG. 1( g) are listed. For pasting, adhesives described later canbe used.

Constitutions of the present optical film when the first phasedifference layer is constituted of a layer A and a layer B or when athird phase difference layer is present are shown in FIG. 2. FIG. 2( c)shows an optical film 100 haying a base material, a layer A, a layer Band a second phase difference layer laminated in this order. FIG. 2( d)shows an optical film 100 having a base material, a first phasedifference layer, a second phase difference layer and a third phasedifference layer laminated in this order. FIG. 2( e) shows an opticalfilm 100 having a base material, a layer B, a layer A and a second phasedifference layer laminated in this order. FIG. 2( f) shows an opticalfilm 100 having a base material, a third phase difference layer, asecond phase difference layer and a first phase difference layerlaminated in this order. FIG. 2( g) shows an optical film 100 having abase material, a second phase difference layer, a layer B and a layer Alaminated in this order. FIG. 2( h) shows an optical film 100 having abase material, a second phase difference layer, a layer A and a layer Blaminated in this order. The present optical films having no basematerial can also be obtained by peeling a base material from these thepresent optical films, and schematic views of the present optical filmshaving no base material are shown in FIG. 2( a) and FIG. 2( b).

In the case of a constitution containing a first phase difference layer,a layer A and a layer B or in the case having a third phase differencelayer, these layers may be laminated on both surfaces of a basematerial. Specifically, for example, FIG. 2( i) shows an optical film100 having a second phase difference layer, a base material, a layer Aand a layer B laminated in this order. FIG. 2( j) shows an optical film100 having a second phase difference layer, a base material, a layer Band a layer A laminated in this order. FIG. 2( k) shows an optical film100 having a firs phase difference layer, a base material, a third phasedifference layer and a second phase difference layer laminated in thisorder. FIG. 2( l) shows an optical film 100 having a first phasedifference layer, a base material, a second phase difference layer and athird phase difference layer laminated in this order. FIG. 2( m) showsan optical film 100 having a third phase difference layer, a basematerial, a first phase difference layer and a second phase differencelayer laminated in this order. FIG. 2( n) shows an optical film 100having a third phase difference layer, a base material, a second phasedifference layer and a first phase difference layer laminated in thisorder. A second phase difference layer, a layer A and a layer B may beformed by direct coating on each layer, or respective lavers may beproduced before pasting them with each other, or respective layers maybe laminated sequentially by transfer.

<Adhesive>

The adhesive includes, for example, a sticky agent, an aqueous adhesiveand an active energy ray curable adhesive.

The sticky agent is obtained, in general, by radical-polymerizing anacrylic monomer mixture containing a (meth)acrylate as the maincomponent and containing a small amount of a (meth)acryl monomer havinga functional group, in the presence of a polymerization initiator, andacrylic sticky agents containing an acrylic resin having a glasstransition temperature Tg of 0° C. or lower and a cross-linking agentare preferably used.

Of (meth)acrylates, alkyl acrylates are preferable, and particularly,n-butyl acrylate, 2-methoxyethyl acrylate and ethoxymethyl acrylate arepreferable.

The (meth)acryl monomer having a functional group as another monomercomponent constituting an acrylic resin is a compound having in themolecule one (meth)acryloyl group as an olefinic double bond and havingin the same molecule a polar functional group such as a hydroxyl group,a carboxyl group, an amide group, an amino group or an epoxy group. Ofthem, preferable are acryl monomers in which the acryloyl group is anolefinic double bond. As examples of such an acryl monomer having afunctional group, 2-hydroxyethyl acrylate is preferable as one having ahydroxyl group, and acrylic acid is preferable as one having a carboxylgroup.

The acryl monomer mixture as a raw material of an acrylic resin mayfurther contain a monomer (hereinafter, referred to as “third monomer”in some cases) other than (meth)acrylates and (meth)acryl monomershaving a functional group described above. Examples thereof includemonomers having in the molecule one olefinic double bond and at leastone aromatic ring, styrenic monomers, (meth)acrylates having in themolecule an alicyclic structure, vinyl monomers, monomers having in themolecule a plurality of (meth)acryloyl groups, and the like.

Especially, the monomers having in the molecule one olefinic double bondand at least one aromatic ring are one of preferable examples. Of then,2-phenoxyethyl (meth)acrylate, 2-(2-phenoxyethoxy)ethyl (meth)acrylate,(meth)acrylate of ethylene oxide-modified nonylphenol,2-(o-phenylphenoxy)ethyl (meth)acrylate are preferable, and of them,2-phenoxyethyl acrylate is further preferable.

The monomers (third monomer) other than (meth)acrylates and (meth)acrylmonomers having a functional group may be used each singly, or differentkinds of them may be used in combination. Structural units derived fromthese third monomers can be present in an amount of usually in the rangeof 0 to 20 wt %, preferably 0 to 10 wt % based on the whole acrylicresin.

It is preferable that the acrylic resin constituting an acrylic stickyagent has a standard polystyrene-equivalent weight-average molecularweight Mw according to gel permeation chromatography (GPC) of 1000000 to2000000. It is preferable that this weight-average molecular weight Mwis 1000000 or more since adhesiveness under high temperature and highhumidity is improved, a possibility of generating floating and peelingbetween a sticky agent layer and a glass base plate constituting aliquid crystal cell tends to decreases, and additionally, a reworkproperty tends to improve. It is preferable that the above-describedweight-average molecular weight Mw of an acrylic resin is 2000000 orless since even if the size of a polarization plate varies, the stickyagent layer follows the size variation, thus, light absence and colorunevenness of a display tend to be suppressed. Further, it is preferablethat the molecular weight distribution represented by the ratio Mw/Mn ofthe weight-average molecular weight Mw to the number-average molecularweight Mn is in the range of 3 to 7.

The acrylic resin contained in an acrylic sticky agent can beconstituted only of a resin having relatively high molecular weight asdescribed above, however, it can also be constituted of a mixture of theresin with other acrylic resin. Examples of the acrylic resin which canbe mixed include those containing as the main component a structuralunit derived from a (meth)acrylate represented by the above-describedformula (I) and having a weight-average weight of 50000 to 300000, andthe like.

The above-described acrylic resin constituting an acrylic sticky agentcan be produced by various known methods such as, for example, asolution polymerization method, an emulsion polymerization method, abulk polymerization method, a suspension polymerization method and thelike. In the production of this acrylic resin, a polymerizationinitiator is usually used. The polymerization initiator includes azocompounds, organic peroxides, inorganic peroxides, redox initiatorsusing a peroxide and a reducing agent together, and the like. Of them,2,2′-azobisisobutyronitrile, benzoyl peroxide, ammonium persulfate andthe like are preferably used. The polymerization initiator is usedusually in a proportion of about 0.001 to 5 parts by mass with respectto 1.00 parts by mass of the total amount of monomers as a raw materialof an acrylic resin.

Thus obtainable acrylic resin is blended with a cross-linking agent toobtain a sticky agent. The cross-linking agent is a compound having inthe molecule at least two functional groups cross-linkable with astructural unit derived from a monomer having a polar functional groupin an acrylic resin, and examples thereof include isocyanate compounds,expoxy compounds, metal chelate compounds, aziridine compounds at thelike.

Of these cross-linking agents, isocyanate compounds are preferably used.The isocyanate compound can be used in the form of a compound having inthe molecule at least two isocyanato groups (—NCO) by itself, andadditionally, in the form of a adduct obtained by reacting it with apolyol, a dimer thereof, a trimer thereof, and the like. Specificexamples thereof include tolylene diisocyanate, an adduct obtained byreacting tolylene diisocyanate with a polyol, a dimer of tolylenediisocyanate, a trimer of tolylene diisocyanate, hexamethylenediisocyanate, an adduct obtained by reacting hexamethylene diisocyanatewith a polyol, a dimer of hexamethylene diisocyanate, a trimer ofhexamethylene diisocyanate, and the like.

The cross-linking agent is blended usually in proportion of about 0.01to 5 parts by mass with respect to 100 parts by mass of an acrylicresin, and preferably blended in a proportion of especially 0.1 to 5parts by mass, further 0.2 to 3 parts by mass. When the blending amountof the cross-linking agent with respect to 100 parts by mass of theacrylic resin is 0.01 part by mass or more, especially 0.1 part by massor more, durability of a sticky agent layer tends to improve.

The sticky agent can also be blended with other components if necessary.The blendable other components include conductive fine particles such asmetal fine particles, metal oxide fine particles or fine particlescoated with a metal and the like, ion conductive compositions, ioniccompounds having an organic cation or anion, silane coupling agents,cross-linking catalysts, weathering stabilizers, tackifiers,plasticizers, softening agents, dyes, pigments, inorganic fillers,resins other than the above-described acrylic resins, light diffusiblefine particles such as organic beads, and the like. Further, it is alsouseful that the sticky agent is blended with an ultraviolet curablecompound, a sticky agent layer is formed, then, cured by irradiatingwith ultraviolet, to give a harder sticky agent layer.

These components constituting a sticky agent are usually dissolved in asuitable solvent such as ethyl acetate and the like and used as a stickyagent composition, A sticky agent layer is obtained by coating a stickyagent composition on a suitable base material and drying thecomposition. Though there are some components undissolvable in asolvent, it may be permissible that the are dispersed in the system.

As the method of forming a sticky agent layer on the present opticalfilm, there are adopted, for example, a method in which a peeling filmis used as a base material, the above-described sticky agent compositionis coated to form a sticky agent layer, and the resultant sticky agentlayer is transferred onto the surface of the present optical film, amethod in which the above-described sticky agent composition is coateddirectly on the surface of the present optical film to form a stickyagent layer, and the like. It is also possible that a sticky agent layeris formed on one peeling film, then, another peeling film is furtherpasted on this sticky agent layer, to give a double-sided separator typesticky agent sheet. Such a double-sided separator type sticky agentsheet is pasted on the present optical film after peeing one peelingfilm in necessary time. Commercially available products of thedouble-sided separator type sticky agent sheet include, for example,non-carrier sticky agent films and non-carrier sticky agent sheetsmarketed from Lintec Corporation and Nitto Denko Corporation.

The peeling film can be, for example, one in which a film made ofvarious resins such as polyethylene terephthalate, polybutyleneterephthalate, polycarbonate, polyacrylate, polypropylene orpolyethylene is used as a base material, and the bonding plane to asticky agent layer of this base material is subjected to a releasingtreatment such as a silicone treatment. Such a peeling film is calledalso a separate film or a separator.

The thickness of a sticky agent layer is preferably 5 to 50 μm, morepreferably 5 to 30 μm. When the thickness of a sticky agent layer is 30μm or less, adhesiveness under high temperature and high humidity isimproved, a possibility of generating floating and peeling between adisplay and a sticky agent layer tends to decreases, and a reworkproperty tends to improve. When the thickness is 5 μm or more, even ifthe size of a polarization plate pasted on this varies, the sticky agentlayer follows the size variation, thus, durability against sizevariation is improved.

The aqueous adhesive is generally a composition using a polyvinylalcohol resin or urethane resin as the main component and in which across-linking agent or curable compound such as isocyanate compounds andepoxy compounds is blended for improving adhesiveness.

In the case of use of a polyvinyl alcohol resin as the main component ofan aqueous adhesive, modified polyvinyl alcohol resins such as acarboxyl group-modified polyvinyl alcohol, an acetoacetyl group-modifiedpolyvinyl alcohol, a methylol group-modified polyvinyl alcohol and anamino group-modified polyvinyl alcohol may be used in addition topartially saponified polyvinyl alcohols and perfectly saponifiedpolyvinyl alcohols. An aqueous solution of such a polyvinyl alcoholresin is used as the aqueous adhesive, and the concentration of thepolyvinyl alcohol resin in the aqueous adhesive is usually 1 to 10 partsby mass, preferably 1 to 5 parts by mass with respect to 100 parts bymass of water.

The aqueous adhesive composed of an aqueous solution of a polyvinylalcohol resin can be blended with a curable compound such as apoly-valent aldehyde, a water-soluble epoxy resin, a melamine compound,a zirconia-based compound and a zinc compound for improving adhesivenessas described above. Examples of the water-soluble epoxy resin includewater-soluble polyamideepoxy resins obtained by reacting epichlorchydrinwith a polyamidepolyamine obtained by a reaction of apolyalkylenepolyamine such as diethylenetriamine andtriethylenetetramine and a dicarboxylic acid such as adipic acid.Commercially available products of such polyamideepoxy resins include“Sumirez Resin 650” and “Sumirez Resin 675” marketed from Sumika ChemtexCo., Ltd., “WS-525” marketed from Nippon PMC Corporation, and the like.When the water-soluble epoxy resin is blended, its addition amount isusually about 1 to 100 parts by mass, preferably 1 to 50 parts by masswith respect to 100 parts by mass of a polyvinyl alcohol resin.

In the case of use of a urethane resin as the main component, of anaqueous adhesive, it effective to use a polyester ionomer type urethaneresin as the main component of an aqueous adhesive. The polyesterionomer type urethane resin referred to here is a urethane resin havinga polyester skeleton and containing a small amount of an ionic component(hydrophilic component) introduced therein. Such an ionomer typeurethane resin can be used as an aqueous adhesive since it is emulsifieddirectly in water to give an emulsion without using an emulsifier. Inthe case of use of the polyester ionomer type urethane resin, it iseffective to blend a water-soluble epoxy compound as a cross-linkingagent. To use the polyester ionomer type urethane resin as an adhesivefor a polarization plate is described, for example, in JP-A No.2005-70140 and JP-A No. 2005-208456.

These components constituting an aqueous adhesive are usually used inthe state of dissolution in water. An adhesive layer is obtained bycoating an aqueous adhesive on a suitable base material and drying this.Components undissolvable in water may be in the state of dispersion inthe system.

The method of forming the above-described adhesive layer on the presentoptical film includes a method of coating the above-described adhesivecomposition directly on the surface of the present optical film to forman adhesive layer, and the like. The thickness of the above-describedadhesive layer is usually about 0.001 to 5 μm, preferably 0.01 μm ormore and preferably 2 μm or less, further preferably 1 μm or less. Whenthe adhesive layer is too thick, the appearance of a polarization platetends to be poor.

For example, if an aqueous adhesive is injected between a polarizationplate and the present optical film and then a thermal cross-linkingreaction is progressed while evaporating water by heating, both thebodies can be endowed with sufficient adhesiveness.

The active energy ray curable adhesive may be one which cures byundergoing irradiation with active energy ray and can adhere apolarization plate and the present optical film at strength sufficientfor practical use. Examples thereof include a cation polymerizableactive energy ray curable adhesive containing an epoxy compound and acation polymerization initiator, a radical polymerizable active energyray curable adhesive containing an acrylic curing component and aradical polymerization initiator, an active energy ray curable adhesivecontaining both a cation polymerizable curing component such as an epoxycompound and a radical polymerizable curing component such as an acryliccompound and blended with a cation polymerization initiator and aradical polymerization initiator, an electron beam curable adhesivewhich cures by irradiating an active energy ray curable adhesivecontaining no initiator with an electron beam, and the like. Preferableis a radical polymerization active energy ray curable adhesivecontaining an acrylic curing component and a radical polymerizationinitiator. Further, a cation polymerizable active energy ray curableadhesive containing an epoxy compound and a cation polymerizationinitiator, which can be used substantially with no solvent, ispreferable.

An active energy ray curable adhesive which is a cation polymerizableepoxy compound, liquid itself at room temperature and has suitableflowability even in the absence of a solvent, for which one givingsuitable curing adhesion strength is selected, and which is blended witha cation polymerization initiator suitable for this is capable ofomitting a drying equipment usually necessary in a step of adhering apolarizer with a transparent protective film in a polarization plateproduction equipment. It is also possible to promote the curing speedand improve the production speed by irradiation with suitable activeenergy dose.

The epoxy compound used in such an adhesive can be, for example, aglycidyl etherified compound of an aromatic compound or linear compoundhaving a hydroxyl group, a glycidyl aminated compound of a compoundhaving an amino group, an epoxide of a linear compound having a C—Cdouble bond, an alicyclic epoxy compound in which a glycidyloxy group oran epoxyethyl group is bonded to a saturated carbocycle directly or viaan alkylene or an epoxy group is bonded to a saturated carbocycledirectly, and the like. The epoxy compounds may be used each singly ordifferent several kinds of them may be used in combination. Of them, analicyclic epoxy compound is preferably used because of excellent cationpolymerizability.

The glycidyl etherified compound of an aromatic compound or linearcompound having a hydroxyl group can be produced, for example, by amethod of addition-condensing epichlorohydrin to a hydroxyl group of thearomatic compound or linear compound under basic condition. Such aglycidyl etherified compound of an aromatic compound or linear compoundhaving a hydroxyl group includes diglycidyl ether of bisphenols,polycyclic aromatic epoxy resins, diglycidyl ether of an alkylene glycolor polyalkylene glycol, and the like.

The diglycidyl ether of bisphenols includes, for example, a glycidyletherified compound of bisphenol A and its oligomer, a glycidyletherified compound of bisphenol F and its oligomer, a glycidyletherified compound of 3,3′,5,5′-tetramethyl-4,4′-bisphenol and itsoligomer, and the like.

The polycyclic aromatic epoxy resin includes, for example, a glycidyletherified compound of a phenol novolak resin, a glycidyl etherifiedcompound of a cresol novolak resin, a glycidyl etherified compound of aphenol aralkyl resin, a glycidyl etherified compound of a naphtholaralykyl resin, a glycidyl etherified compound of a phenoldicyclopentaediene resin, and the like. Further, a glycidyl etherifiedcompound of trisphenols and is oligomer, and the like, are also includedin the polycyclic aromatic epoxy resin.

The digllycidyl ether of an alkylene glycol or polyalkylene glycolincludes, for example, a glycidyl etherified compound of ethyleneglycol, a glycidyl etherified compound of diethylene glycol, a glycidyletherified compound of 1,4-butanediol, a glycidyl etherified compound ofa 1,6-hexanediol, and the like.

The glycidyl aminated compound of a compound having an amino group canbe produced, for example, by a method of addition-condensingepichlorohydrin to an amino group of compound under basic condition. Thecompound having an amino group may have a hydroxyl group simultaneously.Such a glycidyl aminated compound of a compound having an amino groupincludes a glycidyl aminated compound of 1,3-phenylenediamine and itsoligomer, a glycidyl aminated compound of 1,4-phenylenediamine and itsoligomer, a glycidyl aminated compound and glycidyl etherified compoundof 3-aminophenol and its oligomer, a glycidyl aminated compound andglycidyl etherified compound of 4-aminophenol and its oligomer, and thelike.

The epoxide of a linear compound having a C—C double bond can beproduced by a method of epoxidizing a C—C double bond of a linearcompound using a peroxide under basic condition. The linear compoundhaving a C—C double bond includes butadiene, polybutadiene, isoprene,pentadiene, hexadiene and the like. Terpenes having a double bond canalso be used as an epoxidation raw material, and linalool is mentionedas an acyclic monoterpene. The peroxide used in epoxidation can be, forexample, hydrogen peroxide, peracetic acid, tert-butyl hydroperoxide orthe like.

The alicyclic epoxy compound in which a glycidyloxy group or epoxyethylgroup is bonded to a saturated carbocycle directly or via an alkylenecan be a glycidyl etherified compound of a hydrogenated polyhydroxycompound obtained by hydrogenating an aromatic ring of an aromaticcompound having a hydroxyl group typified by bisphenols mentioned above,a glycidyl etherified compound of a cycloalkane compound having ahydroxyl group, an epoxide of a cycloalkane compound having a vinylgroup, or the like.

As the epoxide explained above, commercially available products can beobtained easily, and examples thereof include “jER” series marketed fromMitsubishi Chemical Corporation, “EPICLON ” marketed from DICCORPORATION, “EPOTOTO (registered trademark)” marketed from Toto KaseiCo., “ADEKA RESIN (registered trademark)” marketed from ADEKACorporation, “DENACOL (registered trademark)” marketed from NagaseChemtex Corporation, “DOWEPOXY” marketed from The Dow Chemical Company,“TEPIC (registered trademark)” marketed from Nissan Chemical Industries,Ltd., and the like, each being a trade name.

By contrast, the alicyclic epoxy compound in which an epoxy group isbonded to a saturated carbocycle directly can be produced, for example,by a method of epoxidizing a C—C double bond of a non-aromatic cycliccompound having a C—C double bond in the ring using a peroxide underbasic condition. The non-aromatic cyclic compound having a C—C doublebond in the ring includes, for example, a compound having a cyclopentenering, a compound having a cyclohexene ring, a polycyclic compound inwhich at least two carbon atoms are further bonded to a cyclopentenering or cyclohexene ring to form an additional ring, and the like. Thenon-aromatic cyclic compound having a C—C double bond in the ring mayhave a C—C double bond outside the ring. Examples of the non-aromaticcyclic compound having a C—C double bond in the ring includecyclohexene, 4-vinylcyclohexene, limonene and α-pinene as a monocyclicmono-terpene, and the like.

The alicyclic epoxy compound in which an epoxy group is bonded directlyto a saturated carbocycle may also be a compound in which at least twoalicyclic structures having an epoxy group bonded directly to the ringas described above are formed in the molecule via a suitable linkinggroup. The linking group referred to here includes, for example, anester bond, an ether bond, an alkylene bond and the like.

Specific examples of the alicyclic epoxy compound in which an epoxygroup is bonded directly to a saturated carbocycle include those listedbelow.

-   -   3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,    -   1,2-epoxy4-vinylcyclohexane,    -   1,2-epoxy4-epoxyethylcyclohexane,    -   1,2-epoxy-1-methyl-4-(1-methylepoxyethyl)cyclohexane,    -   3,4-epoxycyclohexylmethyl (meth)acrylate,    -   adduct of 2,2-bis(hydroxymethyl)-1-butanol with        4-epoxyethyl-1,2-epoxycyclohexane,    -   ethylene bis(3,4-epoxycyclohexanecarboxylate),    -   oxydiethylene bis(3,4-epoxycyclohexanecarboxylate,    -   1,4-cyclohexanedimethyl bis(3,4-epoxycyclohexanecarboxylate),    -   3-(3,4-epoxycyclohexylmethoxycarbonyl)propyl        3,4-epoxycyclohexanecarboxylate, and the like.

Also as the alicyclic epoxy compound in which an epoxy group is bondeddirectly to a saturated carbocycle explained above, commerciallyavailable products can be obtained easily, and examples thereof include“CELLOXIDE” series and “CYCLOMER” marketed from Daicel Corporation,“CYRACURE WR” series marketed from The Dow Chemical Company, and thelike, each being a trade name.

The curable adhesive containing an epoxy compound may further contain anactive energy ray curable compound other than the epoxy compound. Theactive energy rev curable compound other than the epoxy compoundincludes, for example, an oxetane compound, an acryl compound and thelike. Of them, an oxetane compound is preferably used in combinationsince the curing speed may possibly be promoted in cationpolymerization.

The oxetane compound is a compound having a 4-membered ring ether in themolecule, and includes, for example, those below.

-   -   1,4-bis[(3-ethyloxetan-3-yl)methoxy methyl]benzene,    -   3-ethyl-3-(2-ethylhexyloxymethyl)oxetane,    -   bis(3-ethyl-3-oxetanylmethyl) ether,    -   3-ethyl-3-(phenoxymethyl)oxetane,    -   3-ethyl-3-(cyclohexyloxymethyl)oxetane,    -   phenol novolak oxetane,    -   1,3-bis[(3-ethyloxetan-3-yl)methoxy]benzene, and the like.

Also as the oxetane compound, commercially available: products can beobtained easily, and examples thereof include “ARON oxetane (registeredtrademark)” series marketed from Toagosei Co., Ltd., “ETERNACOLL(registered trademark)” series marked from UBE Industries, Ltd., and thelike, each being a trade name.

As the curable compound including epoxy compounds and oxetane compounds,those not diluted with an organic solvent or the like are preferablyused, for adhesives blended with them to contain no solvent. Alsoregarding trace components including a cation polymerization initiatorand a sensitizer described later as other components constituting theadhesive, a powder or liquid composed singly of the compound from whichan organic solvent has been removed or dried is used more preferablythan those dissolved in an organic solvent.

The cation polymerization initiator is a compound generating cationspecies by undergoing irradiation with active energy ray, for example,ultraviolet. The initiator may advantageously be one which gives theadhesion strength and the curing speed required by an adhesive blendedwith it, and examples thereof include aromatic diazonium salts; oniumsalts such as an aromatic iodonium salt and an aromatic sulfonium salt;an iron-arene complex, and the like. These cation polymerizationinitiators may be used each singly or different several kinds of themmay be used in combination.

The aromatic diazonium salt includes, for example, those as listedbelow,

-   -   benzenediazonium hexafluoroantimonate,    -   benzenediazonium hexafluorophosphate,    -   benzenediazonium hexafluoroborate, and the like.

The aromatic iodonium salt includes, for example, the as listed below.

-   -   diphenyliodonium tetrakis(pentafluorophenyl)borate    -   diphenyliodonium hexafluorophosphate,    -   diphenyliodonium hexafluorocantimonate,    -   bis(4-nonylphenyl)iodonium hexafluorophosphate, and the like.

The aromatic sulfonium salt includes, for example, those as listedbelow.

-   -   triphenylsulfonium hexafluorophosphate,    -   triphenyulfulfonium hexafluoroantimonate,    -   triphenylsulfonium tetrakis(pentafluorophenyl)borate,    -   diphenyl(4-phenylthiophenyl)sulfonium hexafluoroantimonate,    -   4,4′-bis(diphenyl sulfonio)diphenyl sulfide        bishexafluorophosphate,    -   4,4′-bis[di(β-hydroxyethoxyphenyl)sulfonic]diphenyl sulfide        bishexafluoroantimonate,    -   4,4′-bis[di(β-hydroxyethoxyphenyl)sulfonic]diphenyl sulfide        bishexafluorophosphate,    -   7-[di(p-toluyl)sulfonio]-2-isopropylthioxanthone        hexafluoroantimonate,    -   7-[di(p-toluyl)sulfonio]-2-isopropylthioxanthone        tetrakis(pentafluorophenyl)borate,    -   4-phenylcarbonyl-4-′-diphenyl sulfonio diphenyl sulfide        hexafluorophosphate,    -   4-(p-tert-butylphenylcarbonyl)-4′-di(p-toluyl)sulfonio diphenyl        sulfide tetrakis(pentafluorophenyl)borate, and the like.

The iron-arene complex includes, for example, those as listed below.

-   -   xylenecyclopentadienyl iron(II) hexafluoroantimonate,    -   cumene-cyclopentadienyl iron(II) hexafluorophosphate,    -   xylenecyclopentadienyl iron(II) tris(trifluoromethylsulfonyl)        methanide, and the like.

Among cation polymerization initiators, aromatic sulfonium salts arepreferably used since these salts show an ultraviolet absorbing propertyin a wavelength region of 300 nm or more, and resultantly, can give anadhesive layer excellent in curability and having good mechanicalstrength and adhesion strength.

Also as the action polymerization initiator, commercially availableproducts can be obtained easily, and examples thereof include “Kayarad(registered trademark)” series marketed from Nippon Kayaku Co., Ltd.“CYRACURE UVI” series marketed from The Dow Chemical Company, photo-acidgenerator “CPI” series marketed from San-Apro Ltd. , photo-acidgenerator “TAZ”, “BBI” and “DTS” marketed from Mideri Kagaku Co., Ltd.,“ADEKA OPTOMER” series marketed from ADEKA Corporation, “RHODORSIL(registered trademark) marketed from Rhodia Ltd.; and the like, eachbeing a trade name.

In an active energy ray curable adhesive, the cation polarizationinitiator is blended in a proportion of usually 0.5 to 20 parts by masswith respect to 100 parts by mass of the total amount of the activeenergy ray curable adhesive, and preferably 1 to 15 parts by mass. whenthe amount is too small, curing becomes insufficient, and the mechanicalstrength and the adhesion strength of so adhesive layer are lowered insome cases. When the amount is too large, the amount of ionic substancesin an adhesive layer increases to raise the hygroscopicity of theadhesive layer, and durability of the resultant polarization plate islowered in some cases.

When an active energy ray curable adhesive is used in the form of theelectron beam curable type, it is not particularly necessary to allow aphotopolymerization initiator to be contained in a composition, whilewhen used in the ultraviolet curable type, it is preferable to use aphoto-radical generator. The photo-radical generator includes a hydrogenabstraction type photo-radical generator and a cleavable photo-radicalgenerator.

The hydrogen abstraction type photo-radical generator includes, forexample, naphthalene derivatives such as 1-methylnaphthalene,2-methylnaphthalene, 1-fluoronaphthalene, 1-chloronaphthalene,2-chloronaphthalene, 1-bromonaphthalene, 2-bromonaphthalene,1-iodonaphthalene, 2-iodonaphthalene, 1-naphthol, 2-naphthol, 1-methoxynaphthalene, 2-methoxy naphthalene, 1,4-dicyanonaphthalene and the like,anthracene derivatives such as anthracene, 1,2-benzanthracene,9,10-dichloroanthracene, 9,10-dibromoanthracene,9,10-diphenylanthracene, 9-cyanoanthracene, 9,10-dicyanoanthracene,2,6,9.10-tetracyanoanthracene and the like, pyrene derivatives,carbazole derivatives such as carbazole, 9-methylcarbazole,9-phenylcarbazole, 9-propen-2-yl-9H-carbazole, 9-propyl-9H-carbazole,9-vinylcarbazole, 9H-carbazole-9-ethanol, 9-methyl-3-nitro-9H-carbazole,9-methyl-3,6-dinitro-9H-carbazole, 9-octanoylcarbazole,9-carbazolemethanol, 9-carbazolepropionic acid 9-carbazolepropionitrile,9-ethyl-3,6-dinitro-9H-carbazole, 9-ethyl-3-nitrocarbazole,9-ethylcarbazole, 9-isopropylcarbazole,9-(ethoxycarbonylmethyl)carbazole, 9-(morpholinomethyl)carbazole,9-acetylcarbazole, 9-allylcarbazole, 9-benzyl-9H-carbazole,9-carbazoleacetic acid, 9-(2-nitrophenyl)carbazole,9-(4-methoxyphenyl)carbazole, 9-(1-ethoxy2-methylpropyl)-9H-carbazole,3-nitrocarbazole, 4-hydroxycarbazole, 3,6-dinitro09H-carbazole,3,6-diphenyl-9H-carbazole, 2-hydroxycarbazole,3,6-diacetyl-9-ethylcarbazole and the like, benzophenone derivativessuch as benzophenone, 4-phenylbenzophenone,4,4′-bis(dimethoxy)benzophenone, 4,4′-bis(dimethylamino)benzophenone,4,4′-bis(diethylamino)benzophenone, methyl 2-benzoylbenzoate,2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone,3,3′-dimethyl-4-methoxybenzophenone, 2,4,6-trimethylbenzophenone and thelike, aromatic carbonyl compounds,[4-(4-methylphenylthio)phenyl]-phenylmethanone, xanthone, thioxanthonederivatives such as thioxanthone, 2-chlorothioxanthone,4-chlorothioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone,2,4-dimethylthioxanthone, 2,4-diethylthioxanthone,1-chloro-4-propoxythioxanthone and the like, coumarin derivatives, andthe like.

The cleavable photo-radical generator is a photo-radical generator ofthe type of being cleaved by irradiation with active energy ray togenerate radicals, and specific examples thereof include, but notlimited to, aryl alkyl ketones such as benzoin ether derivatives,acetophenone derivatives and the like, oxime ketones, acylphosphineoxides, S-phenyl thiobenzoates, titanocenes, and derivatives obtained byincreasing the molecular weight of them. Commercially availablecleavable photo-radical generators include, but not limited to,1-(4-dodecylbenzoyl)-1-hydroxy-1-methylethane,1-(4-isopropylbenzoyl)-1-hydroxy-1-methylethane,1-benzoyl-1-hydroxy-1-methylethane,1-[4-(2-hydroxyethoxy)-benzoyl]-1-hydroxy-1-methylethane,1-[4-(acryloyloxyethoxy)-benzoyl]-1-hydroxy-1-methylethane, diphenylketone, phenyl-1-hydroxycyclohexyl ketonhe, benzyldimethyl ketal,bis(cyclopentadienyl)-bis(2,6-difluoro-3-pyrryl-phenyl)titanium,(η6-isopropylbenzene)-(η5-cyclopentadienyl)-iron(II)hexafluorophosphate, trimethylbenzoyl diphenylphosphineoxide,bis(2,6-dimethoxy-benzoyl)-(2,4,4-trimethyl-pentyl)-phosphineoxide,bis(2,4,6-trimethylbenzoyl)-2,4-dipentoxyphenylphosphineoxide orbis(2,4,6-trimethylbenzoyl)phyenylphosphineoxide,(4-morpholinobenzoyl)-1-enzyl-1-dimethylaminopropane,4-(methylthiobenzoyl)-1-methyl-1-morpholinoethane, and the like.

Regarding photo-radical generators contained in electron beam curabletype adhesives among active energy ray curable adhesives used in thepresent invention, namely with respect to hydrogen abstraction type orcleavable photo-radical generators, any of them can be used singly, andadditionally, several members of them may be used in combination, andmore preferable is a combination with at least one cleavablephoto-radical generator from the standpoint of stability of a singlebody of the photo-radical generator and curability thereof. Of cleavablephoto-radical generators, acylphosphine oxides are preferable, and morespecifically, trimethylbenzoyl diphenylphosphine oxide (trade name“DAROCURE TPO”; Ciba Japan K.K.),bis(2,6-dimethoxy-benzoyl)-(2,4,4-trimethyl-pentyl)-phosphineoxide(trade name “CGI 403”; Ciba Japan K.K.) orbis2,4,6-trimethylbenzoyl)-2,4-dipentoxyphenylphosphineoxide (trade name“Irgacure819”; Ciba Japan K.K.) is preferable.

The active energy ray curable adhesive can contain a sensitizer ifnecessary. By use of a sensitizer, reactivity improves, and themechanical strength and the adhesion strength of an adhesive layer canbe further improved. As the sensitizer, those described above can beappropriately used.

When a sensitizer is blended, the blending amount is preferably in therange of 0.1 to 20 parts by mass with respect to 100 parts by mass ofthe total amount of an active energy ray curable adhesive.

Various additives can be blended in an active energy ray curableadhesive in a range wherein its effect is not deteriorated. Additiveswhich can be blended include, for example, an ion trapping agent, anantioxide, a chain transfer agent, a tackifier, a thermoplastic resin, afiller, a flow controlling agent, a plasticizer, a defoaming agent andthe like.

These components constituting an active energy ray curable adhesive areused usually in the state of dissolution in a solvent. When an activeenergy ray curable adhesive contains a solvent, an adhesive layer isobtained by coating an active energy ray curable adhesive on a suitablebase material and drying this. Components undissolvable in a solvent maybe in the state of dispersion in the system.

The method of forming the above-described adhesive layer on the presentoptical film includes a method of coating the above-described adhesivecomposition directly on the surface of the present optical film to forman adhesive layer, and the like. The above-described adhesive layer hasa thickness of usually about 0.001 to 5 μm, preferably 0.01 μm or more,and preferably 4 μm or less, further preferably 3 μm or less. When theadhesive layer is too thick, the appearance of a polarization platetends to be poor.

An active energy ray curable adhesive can be coated on a film by coatingmethods described above. In this case, the viscosity of an active energyray curable adhesive may be one at which the adhesive can be coated byvarious methods, and the viscosity at 25° C. is preferably in the rangeof 10 to 30000 mPa·sec, more preferably in the range of 80 to 6000mPa·sec. When the viscosity is too low, there is a tendency that auniform coated film having no unevenness is not obtained easily. Incontrast, when the viscosity is too high, the adhesive does not floweasily, and there occurs a tendency that a uniform coated film having nounevenness is not obtained easily. The viscosity referred to heredenotes a value measured at 60 rpm after adjusting the adhesive to 25°C. using a B-type viscometer.

The above-described active energy ray curable adhesive can be used inthe mode of the electron beam curable type or the ultraviolet curabletype. The active energy ray in the present invention is defined asenergy ray capable of decomposing a compound generating active species,to cause generation of active species. Such active energy ray includesvisible light, ultraviolet ray, infrared ray, X-ray, α ray, β ray, γray, electron beam and the like.

In the electron beam curable type, any suitable conditions can beadopted as the electron beam irradiation condition providing that theabove-described active energy ray curable adhesive can be cured. Inelectron beam irradiation, for example, the accelerating voltage ispreferably 5 kV to 300 kV, further preferable 10 kV to 250 kV. When theaccelerating voltage is less than 5 kV, there is a possibility that anelectron beam doe snot reach an adhesive to cause poor curing, whilewhen the accelerating voltage is over 300 kV, there is a possibilitythat force penetrating through a sample is too high and an electron beambounces around to damage a transparent protective film and a polarizer.The irradiation dose is 5 to 100 kGy, further preferably 10 to 75 kGy.When the irradiation dose is less than 5 kGy, an adhesive lacks curing,while when over 100 kGy, a transparent protective film and a polarizerare damaged, lowering of mechanical strength and yellowing occur, andthe desired optical property cannot be obtained.

Electron beam irradiation is usually carried out in an inert gas,however, if necessary, may also be carried out in atmospheric air orunder condition in which the oxygen content is increased slightly.Though varying depending on the material of a transparent protectivefilm, damage to a transparent protective film can be prevented byintentionally causing oxygen block on the face of the transparentprotective film initially hit by an electron beam by appropriateintroduction of oxygen, and by this, only an adhesive can be irradiatedwith an electron beam efficiently.

In the ultraviolet curable type, the irradiation intensity of an activeenergy ray curable adhesive is determined depending on the compositionof each adhesive and is not particularly restricted, however, it ispreferably 10 to 5000 mW/cm². When the irradiation intensity on a resincomposition is less than 10 mW/cm², the reaction times becomes toolonger, while when over 5000 mW/cm², there is a possibility ofoccurrence of yellowing of the adhesive constitution material anddeterioration of a polarizer by heat radiated from a light source andheat generation in polymerizable of the composition. The irradiationintensity is preferably intensity in a wavelength region effective foractivation of a photo-cation polymerization initiator, more preferablyintensity in a wavelength region of 400 nm or less, further preferablyintensity in a wavelength region of 280 to 320 nm. It is preferable thatirradiation is conducted once or several times under such irradiationintensity to give the accumulated light quantity set at 10 mJ/cm², ormore, preferably at 10 to 5000 mJ/cm². When the accumulated lightquantity on the above-described adhesive is less than 10 mJ/cm²,generation of active species derived from a polymerization initiator isnot sufficient and curing of the adhesive becomes insufficient. Incontrast, when the accumulated light quantity is over 5000 mJ/cm², theirradiation time becomes very long, generating a disadvantage forimprovement of productivity. In this case, which wavelength region (UVA(320 to 390 nm), UVB (280 to 320 nm), and the like) is necessary todetermine the accumulated light quantity varies depending on a film tobe used and a combination of adhesive species.

The light source used for conducting polymerizable and curing of anadhesive by irradiation with active energy ray in the present inventionis not particularly restricted and includes, for example, a low pressuremercury lamp, a medium pressure mercury lamp, a high pressure mercurylamp, an ultrahigh pressure mercury lamp, a xenon lamp, a halogen lamp,a carbon arc lamp, a tungsten lamp, a gallium lamp, excimer laser, a LEDlight source emitting in the wavelength range of 380 to 440 nm, achemical lamp, a black light lamp, a microwave excitation mercury lampand a metal halide lamp. The light source is preferably an ultravioletlight source having emission distribution at wavelengths of 400 nm orless from the standpoint of stability of energy and simplicity of theapparatus.

[Circular Polarization Plate]

The present optical film can be combined with a polarization plate toobtain a circular polarization plate having the present optical film anda polarization plate (hereinafter, referred to as the present circularpolarization plate in some cases). The present optical film and apolarization plate are usually pasted with an adhesive. Preferably,these are pasted with an active energy ray curable adhesive.

When a first phase difference layer is constituted of only one layer andonly one slow axis exists, it is preferable that the transmission axisof the polarization plate is substantially 45° to the slow axis (opticalaxis) of the first phase difference layer of the present optical film.Substantially 45° usually denotes a range of 45±5°. FIG. 3 shows aschematic view of the present circular polarization plate 110.

The polarization plate used in the present circular polarization plateshown in FIG. 3 may be one having a protective film on one surface of apolarizer or one having a protective film on both surfaces of apolarizer. FIG. 3( c) to FIG. 3( h) show a circular polarization platecomposed of the present optical film having first and second phasedifference layers formed on a base material, and these base materialscan perform also a function as a protective film for the other surfacein the case of use of a polarization plate having a protective film onone surface of a polarizer. In the constitutions shown in FIG. 3( a) andFIG 3(b), the present optical film having no base material is laminated,and a polymerizable liquid crystal composition may be coated directly ona polarization plate to form a phase difference layer, a phasedifference layer may be pasted on the surface of a polarizer with anadhesive, or a phase difference layer may be pasted on a polarizationplate with an adhesive.

The method of pasting the present optical film having no base materialto other base materials such as the surface of a polarizer, apolarization plate and the like includes a method in which the presentoptical film having deprived of a base material is pasted to other basematerial with an adhesive, a method in which the present optical film ispasted to other base material with an adhesive, then, a base material isremoved, and the like. In this case, an adhesive may be coated on theside of a phase difference layer of the present optical film or may becoated on the side of other base material. When an orientation film ispresent between a base material and a phase difference layer, also theorientation film may be removed together with the base material.

A base material having on the surface a functional group forming achemical bond to a phase difference layer, an orientation film or thelike forms a chemical bond to the phase difference layer, theorientation film or the like, that is, there is a tendency that the basematerial is not easily removed. Therefore, when a base material isremoved by peeling, base materials having few functional group on thesurface are preferable, and base materials not undergone a surfacetreatment for forming functional groups on the surface are preferable.

In the case of an orientation film having a functional group forming achemical bond to a base material, close adherence between the basematerial and the orientation film tends to be large, therefore,orientation films having few functional groups forming a chemical bondto a base material are preferable when the base material is removed bypeeling. It is preferable that a reagent cross-linking a base materialand an orientation film is not contained, and further, it is preferablethat components such as a solvent and the like dissolving a basematerial are not contained in a solution of an orienting polymercomposition, a photo-orientation film forming composition or the like.

In the case of an orientation film having a functional group forming achemical bond to a phase difference layer, close adherence between thephase difference layer and the orientation film tends to increase.Therefore, orientation films having few functional groups forming achemical bond to a phase difference layer are preferable when theorientation film is removed together with a base material. It ispreferable that a reagent cross-linking a phase difference layer and anorientation film is not contained in the phase difference layer and theorientation film.

In the case of a phase difference layer having a functional groupforming a chemical bond to an orientation film, close adherence betweenthe orientation film and the phase difference layer tends to increase.Therefore, phase difference layers having few functional groups forminga chemical bond to a base material or an orientation film are preferablewhen the base material is removed or when the orientation film isremoved together with the base material. It is preferable that a reagentcross-linking a base material or an orientation film and a phasedifference layer is not contained in a polymerizable liquid crystalcomposition.

For example, if an adhesive is coated on the surface of a first phasedifference layer of the present optical film having a base material, asecond phase difference layer and a first phase difference layerlaminated in this order and a polarization plate is pasted to thisbefore removing the base material of the present optical film, acircular polarization plate having a constitution shown in FIG. 3(ahaving the polarization plate, the first phase difference layer and thesecond phase difference layer laminated in this order can be produced.Further, if an adhesive is coated on the surface of a second phasedifference layer of the present optical film having a base material, afirst phase difference layer and a second phase difference layerlaminated in this order and a polarization plate is pasted to thisbefore, removing the base material of the present optical film, acircular polarization plate having a constitution shown in FIG. 3( b)having the polarization plate, the second phase difference, layer andthe first phase difference layer laminated in this order can beproduced.

In constitutions shown in FIG. 3( i) to FIG. 3( n), the present opticalfilm having two base materials is laminated.

The constitution of the present circular polarization plate in which afirst phase difference layer contains a layer A and a layer B or a thirdphase difference layer is contained is shown in FIG. 4. in the case of aconstitution containing a layer A and a layer B or a third phasedifference layer, the position of lamination of a polarization plate isrestricted.

Specifically, in the case of lamination of a layer A having a phasedifference of λ/4 and a layer B having a phase difference of λ/2, first,the layer B is formed so that the slow axis of the layer B makes anangle of 75° and then, the layer A is formed so that the slow axis ofthe layer A makes an angle of 15° to the absorption axis of apolarization plate.

Further, when a first, phase difference layer having a phase differenceof λ/4 and a third phase difference layer having a phase difference ofλ/2 are contained, first, the third phase difference layer is formed sothat the slow axis of the third phase difference layer makes an angle of75° and then, the first phase difference layer is formed so that theslow axis of the first phase difference layer makes an angle of 15° tothe absorption axis of a polarization plate. Though the position of asecond phase difference layer is not restricted, it is necessary that apolarization plate, at layer B and a layer A are laminated in this orderor a polarization plate, a third phase difference layer and a firstphase difference layer are laminated in this order. By laminating asdescribed above, it is possible for the resultant circular polarizationplate to manifest a function as a wide band λ/4 plate. Here, the angleof the axis forming a layer A and a layer B is not restricted and layerscan be laminated by a desired method since it is known, as described,for example, in JP-A No. 2004-126538, that if the angles of the slowaxes of a layer A and a layer B are 30° and −30° or 45° and −45° to theabsorption axis of a polarization plate, a function as a wide band λ/4plate can be manifested.

Though the present optical film having no base material is laminated inconstitutions shown in FIG. 4( a) and FIG. 4( b), a circularpolarization plate having these constitutions can be produced by thesame method as the production method of a circular polarization platehaving the constitution shown in FIG. 3( a) and FIG. (3 b).

The present circular polarization plate can be used in various displays,and particularly, can be effectively used in an organicelectroluminescence display and an inorganic electroluminescence (EL)display, and an organic electroluminescence display having a touchpanel.

<Polarization Plate>

The polarization plate may advantageously be a film having apolarization function. This film includes a drawn film containing anadsorbed pigment having absorption anisotropy, a film containing as apolarizer a film coated with a pigment having absorption anisotropy, andthe like. The pigment having absorption anisotropy includes, forexample, dichroic pigments.

The film containing as a polarizer a drawn film containing an adsorbedpigment having absorption anisotropy is fabricated usually by applying atransparent protective film via an adhesive to at least one surface of apolarizer produced via a step of uniaxially drawing a polyvinyl alcoholresin film, a step of dyeing the polyvinyl alcohol resin film with adichroic pigment to allow the dichroic pigment to be adsorbed, a steptreating the polyvinyl alcohol resin film containing the absorbeddichroic pigment with a boric acid aqueous solution, and a step ofperforming washing with water after treatment with a boric acid aqueoussolution.

The polyvinyl alcohol resin is obtained by saponifying a polyvinylacetate resin. As the polyvinyl acetate resin, copolymers of vinylacetate and other monomers copolymerizable with vinyl acetate are used,in addition to polyvinyl acetate as a homopolymer of vinyl acetate. Theother monomers copolymerizable with vinyl acetate include, for example,unsaturated carboxylic acids, olefins, vinyl ethers, unsaturatedsulfonic acids, acrylamides having an ammonium group, and the like.

The degree of saponification of the polyvinyl alcohol resin is usuallyabout 85 to 100 mol %, preferably 98 mol % or more. The polyvinylalcohol resin may be modified, and for example, polyvinylformal andpolyvinylacetal modified with aldehydes can also be used. The degree ofpolymerization of the polyvinyl alcohol resin is usually about 1000 to10000, preferably in the range of 1500 to 5000.

A film formed of such a polyvinyl alcohol resin is used as an originalfilm of a polarization plate. The method of forming a film of apolyvinyl alcohol resin is not particularly restricted, and its filmformation can be conducted by known methods. The thickness of apolyvinyl alcohol original film can be, for example, about 10 to 150 μm.

Uniaxial drawing of a polyvinyl alcohol resin film can be conductedbefore dyeing with a dichroic pigment, simultaneously with dyeing orafter dyeing. When uniaxial drawing is conducted after dyeing, thisuniaxial drawing may be conducted before a boric acid treatment orconducted during a boric acid treatment. Further, it is also possible toperform uniaxial drawing in these several stages. In uniaxial drawing,drawing may be conducted uniaxially between rolls having differentcircumferential velocities, or drawing may be conducted uniaxially usinga hot roll. Uniaxial drawing may be dry drawing in which drawing isconducted in atmospheric air or may be wet drawing in which a polyvinylalcohol resin film is swollen and drawn under the swollen condition. Thedrawing magnification is usually about 3 to 8 times.

Dyeing of a polyvinyl alcohol resin film with a dichroic pigment iscarried out, for example, by a method of immersing a polyvinyl alcoholresin film in an aqueous solution containing a dichroic pigment.

As dichroic pigment, specifically, iodine and dichroic organic dyes areused. The dichroic organic the includes dichroic direct dyes composed ofa disazo compound such as C.I. DIRECT RED 39 and the like and dichroicdirect dyes composed of a compound such as trisazo, tetrakisazo and thelike. It is preferable that a polyvinyl alcohol resin film is subjectedpreviously to a treatment of immersing into water before the dyeingtreatment.

When iodine is used as the dichroic pigment, a method of immersing apolyvinyl alcohol resin film in an aqueous solution containing iodineand potassium iodide to dye the film is usually adopted. The content ofiodine in this aqueous solution is usually about 0.01 to 1 part by massper 100 parts by mass of water. The content of potassium iodide isusually about 0.5 to 20 parts by mass per 100 parts by mass of water.The temperature of an aqueous solution used for dyeing is usually about20 to 40° C. The time of immersion into this aqueous solution (dyeingtime) is usually about 20 to 1800 seconds.

In contrast, when a dichroic organic dye is used as the dichroicpigment, a method of immersing a polyvinyl alcohol resin film in anaqueous solution containing a water-soluble dichroic dye to dye the filmis usually adopted. The content of a dichroic organic dye in thisaqueous solution is usually about 1×10⁻⁴ to 10 parts by mass, preferably1×10⁻³ to 1 part by mass, further preferably 1×10⁻³ to 1×10⁻² part bymass per 100 parts by mass of water. This aqueous solution may alsocontain an inorganic salt such as sodium sulfate as a dyeing aid. Thetemperature of a dichroic dye aqueous solution used for dyeing isusually about 20 to 80° C. The time of immersing into this aqueoussolution (dyeing time is usually about 10 to 1800 seconds.

The boric acid treatment after dyeing with a dichroic pigment can beconducted usually by a method of immersing the dyed polyvinyl alcoholresin film in a boric acid aqueous solution. The content of boric acidin this boric acid aqueous solution is usually about 2 to 15 parts bymass, preferably 5 to 12 parts by mass per 100 parts by mass of water.When iodine is used as the dichroic pigment, it is preferable that thisboric acid aqueous solution contains potassium iodide, and in this case,the content of potassium iodide is usually about 0.1 to 15 parts bymass, preferably 5 to 12 parts by mass per 100 parts by mass of water.The time of immersing into a boric acid aqueous solution is usuallyabout 60 to 1200 seconds, preferably 150 to 600 seconds, furtherpreferably 200 to 400 seconds. The temperature of the boric acidtreatment is 50° C. or more, preferably 50 to 85° C. further preferably50 to 80° C.

The polyvinyl alcohol resin film after the boric acid treatment isusually treated by washing with water. The water-washing treatment canbe conducted, for example, by a method of immersing the polyvinylalcohols resin film treated with boric acid in water. The temperature ofwater in the water-washing treatment is usually about 5 to 40° C. Theimmersing time is usually about 1 to 120 seconds.

After washing with water, a drying treatment is performed to obtain apolarizer. The drying treatment can be conducted by using, for example,a hot air drier and a far infrared heater. The temperature of the dryingtreatment is usually about 30 to 100° C., preferably 50 to 80° C. Thetime of the drying treatment is usually about 60 to 600 seconds,preferably 120 to 600 seconds. By the drying treatment, the moisturepercentage of polarizer is lowered to about practical level. Itsmoisture percentage is usually about 5 to 20 wt %, preferably 8 to 15 wt%. When the moisture percentage is lower than 5 wt %, flexibility ofpolarizer is lost, and a polarizer is damaged or broken after drying insome cases. When the moisture percentage is over 20 wt %, there is apossibility of deterioration of thermal stability of a polarizer.

The thickness of a polarizer obtained by thus subjecting a polyvinylalcohol resin film to uniaxial drawing, dyeing with a dichroic pigment,a boric acid treatment, washing with water and drying is preferably 5 to40 μm.

The film coated with a pigment having absorption anisotropy includesfilms obtained by coating a composition containing a dichroic pigmenthaving liquid crystallinity or a composition containing a dichroicpigment and a polymerizable liquid crystal, and the like. This filmpreferably has a protective film on one or both surfaces thereof. As theprotective film, the same materials as the base material described aboveare mentioned.

With respect to the film coated with a pigment having absorptionanisotropy, the smaller thickness is more preferable, however, when toothin, there is a tendency of lowering of strength, leading to poorworkability. The thickness of this film is usually 20 μm or less,preferably 5 μm or less, more preferably 0.5 μm or more and 3 μm orless.

The film coated with a pigment having absorption anisotropy includes,specifically, films described in JP-A No. 2012-33249 and the like.

A polarization plate is obtained by laminating a transparent protectivefilm on at least one surface of thus obtained polarizer via an adhesive.As the transparent described above can be preferably used, and theoptical film of the present invention can also be used.

The present optical film and the present circular polarization plate canbe used in various displays.

The display is an apparatus having a display element, and contains alight emitting device or light emitting apparatus as a light emittingsource. The display includes a liquid crystal display, an organicelectroluminescence (EL) display, an inorganic electroluminescence (EL)display, a touch panel display, an electron emission display (forexample, field emission display (FED), surface field emission display(SED)), an electron paper (a display using an electron ink and anelectrophoresis element), a plasma display, a projection type display(for example, a grating light valve (GLV) display, a display having adigital micro mirror device (DMD)), an piezoelectric ceramic display,and the like. The liquid crystal display includes any of a transmissiontype liquid crystal display, a semi-transmission type liquid crystaldisplay, a reflective liquid crystal display, a direct view liquidcrystal display, a projection liquid crystal display and the like. Thesedisplays may be a display displaying a two dimensional image or a stereodisplay displaying a three dimensional image. Particularly, the presentcircular polarization plate can be effectively used in an organicelectroluminescence (EL) display and an inorganic electroluminescence(EL) display, and the present optical compensation polarization platecan be effectively used in a liquid crystal display and a touch paneldisplay.

FIG. 5 is a schematic view of an organic EL display 200 equipped withthe present circular polarization plate.

FIG. 5( a) shows an organic EL display 200 having a polarization plate6, a first phase difference layer 1, a second phase difference layer 2and an organic EL panel 7 laminated in this order. FIG. 5( c) shows anorganic EL display 200 having a polarization plate 6, a base material 3,a first phase difference layer 1, a second phase difference layer 2 andan organic EL panel 7 laminated in this order. In FIGS. 5( b), (d) to(h), the lamination order is different from that in FIGS. 5( a) and (c).

The method of laminating a polarization plate, the resent optical filmand an organic EL panel includes a method of pasting the presentcircular polarization plate prepared by laminating a polarization plateand the present optical film to an organic EL panel, a method of pastingthe present optical film to an organic EL panel and further casting apolarization plate on the surface of the present optical film, and thelike. For pasting, an adhesive is usually used.

For example, an organic EL display 200 shown in FIG. 5( a) can beproduced by coating an adhesive on the surface of a second phasedifference layer 2 of the present circular polarization plate shown inFIG. 3( a) and pasting an organic EL panel 7 to this. Further, anorganic EL display 200 shown in FIG. 5( a) can also be produced bycoating an adhesive on the surface of a second phase difference layer 2of the present optical film shown in FIG. 1( b), pasting an organic ELpanel 7 to this, removing a base material 3 of the present optical film,coating an adhesive on the surface of a first phase difference layer 1emerged by removal of the base material, and pasting a polarizationplate 6 to this.

FIG. 6 is a schematic view showing an organic EL display 30. The organicEL display 30 shown in FIG. (6) has the present circular polarizationplate 31, and in this display, a light emitting layer 35 and a cathodeelectrode 36′ a laminated on a base plate 32 carrying a pixel electrode34 formed via an interlayer insulation film 33. The present circularpolarization plate 31 is disposed on the side composite to the lightemitting layer 35 sandwiching the base plate 32. The light emittinglayer 35 emits light when plus voltage is applied to the pixel electrode34, minus voltage is applied to the cathode electrode 36, and directcurrent is applied between the pixel electrode 34 and the cathodeelectrode 36. The light emitting layer 35 is composed of an electrontransporting layer, a light emitting layer, a hole transporting layerand the like. Light emitted from the light emitting layer 35 penetratesthe pixel electrode 34, the interlayer insulation film 33, the baseplate 32 and the present circular polarization plate 31.

For producing the organic EL display 30, first, a thin. film transistor38 is formed in the desired shape on the base material 32. Then, theinterlayer insulation film 33 is formed, then, the pixel electrode 34 isformed is formed by a sputtering method, and patterned. thereafter, thelight emitting layer 35 is laminated.

Then, the present circular polarization plate 31 is provided on thesurface opposite to the surface of the base plate 32 on which the thinfilm transistor 38 is provided. In this case, the present circularpolarization plate 31 is disposed so that the polarization plate of thepresent circular polarization plate 31 faces the outside (side oppositeto the base plate 32).

The base plate 32 includes ceramic base plates such as a sapphire glassbase plate, a quartz glass base plate, soda glass base plate and aluminaand the like; metal base plates such as copper and the like; plasticbase plates, and the like. Though not illustrated, a heat conductivefilm may be formed on the base plate 32. The heat conductive filmincludes a diamond thin film (DLC, etc.) and the like. When the pixelelectrode 34 is of reflective type, light emits to a direction oppositeto the base plate 32. Therefore, not only transparent materials, butalso nonpermeable materials such as stainless and the like can be used.The base plate may be formed of a single body, or a plurality of baseplates may be pasted with an adhesive to form a laminated base plate.These base plates are not limited to those in the form of a plate, andmay also be in the form of a film.

As the thin film transistor 38, for example, a polycrystalline silicontransistor and the like may be used. The thin film transistor 38 isprovided at the end of the pixel electrode 34, and its size is about 10to 30 μm. The size of the pixel electrode 34 is about 20 μm×20 to 300μm×300 μm.

On the base plate 32, a wiring electrode of the thin film transistor 38is provided. The wiring electrode has low resistance and has a functionof electrically connecting to the pixel electrode 34 to suppress theresistance value low, and in general, one containing one or more of A1,transition metals (excluding Ti), Ti and titanium nitride (TiN) is usedas the wiring electrode.

The interlayer insulation film 33 is provided between the thin filmtransistor 38 and the pixel electrode 34. The interlayer insulation film33 may be any film having an insulating property such as films ofinorganic materials such as silicon oxide like SiO₂ or the like, siliconnitride and the like formed by sputtering and vacuum vapor deposition,silicon oxide layers formed by SOG (spin on glass), photoresists, coatedfilms of resin materials such as polyimide and acrylic resins and thelike.

A rib 39 is formed on the interlayer insulation film 33. The rib 39 isdisposed on peripheral parts of the pixel electrode 34 (between adjacentpixels). The material of the rib 39 includes acrylic resins, polyimideresins and the like. The thickness of the rib 39 is preferably 1.0 μm ormore and 3.5 μm or less, more preferably 1.5 μm or more and 2.5 μm orless.

Next, an EL device composed of the pixel electrode 34, the lightemitting layer 35 and the cathode electrode 36 will be explained. Thelight emitting layer 35 has at least one hole transporting layer and atleast one light emitting layer, and has, for example, an electroninjection transporting layer, a light emitting layer, a holetransporting layer and a hole injection layer in series.

The pixel electrode 34 includes, for example, ITO (tin-doped indiumoxide), IZO (zinc-doped indium oxide), IGZO, ZnO, SnO₂ and In₂O₃ and thelike, and particularly, ITO and IZO are preferable. The pixel electrode35 may have a thickness not lower than a certain level at which holeinjection can be conducted sufficiently, and the thickness is preferablyabout 10 to 500 nm.

The pixel electrode 34 can be formed by a vapor deposition method(preferably, a sputtering method). The sputtering gas is notparticularly restricted, and inert gases such as Ar, He, Ne, Kr, Xe andthe like or a mixed gas thereof may be used.

As the constituent material of the cathode electrode 36, for example,metal elements such as K, Li, Na, Mg, La, Ce, Ca, Sr, Ba, Al, Ag, In,Sn, Zn, Zr and the like may be used, and for improving operatingstability of an electrode, it is referable to use an alloy systemcomposed of two components or three components selected from theexemplified metal elements. The alloy system preferably includes, forexample, Ag.Mg(Ag: 1 to 20 at %), Al.Li(Li: 0.3 to 14 at %), In.Mg(Mg:50 to 80 at %), Al.Ca(Ca: 5 to 20 at %) and the like.

The cathode electrode 36 is formed by a vapor deposition method, asputtering method and the like. It is preferable that the thickness ofthe cathode electrode 37 is 0.1 nm or more, preferably 1 to 500 nm nomore.

The hole injection has a function of making injection of holes from thepixel electrode 34 easy, the hole transporting layer has a function oftransporting holes and a function of preventing electrons, and these arealso called a charge injection layer or a charge transporting layer.

The thickness of a light emitting layer, the total thickness of a holeinjection layer and a hole transporting layer, and the thickness of anelectron injection transporting layer are not particularly restricted,and preferably about 5 to 100 nm, though varying depending on theformation method. In a hole injection layer and a hole transportinglayer, various organic compounds can be used. For formation of a holeinjection transporting layer, a light emitting layer and an electroninjection transporting layer, a vacuum vapor deposition method can beused since a homogeneous thin film can be formed.

As the light emitting layer 35, use can be made of one utilizing lightemission (fluorescence) from a singlet exciton, one utilizing lightemission (phosphorescence) from a triple exciton, one containing oneutilizing light emission (fluorescence) from a single exciton and oneutilizing light emission (phosphorescence) from a triplet exciton, oneformed of an organic substance, one containing one formed of an organicsubstance and one formed of an inorganic substance, one containing ahigh molecular weight material, one containing a low molecular weightmaterial, one containing a high molecular weight material and a lowmolecular weight material, and the like. The layer is not limited tothem, and light emitting layers 35 formed by using various materialsknown for an EL device can be used in the organic EL display 30.

A desiccant (not shown) is disposed in a space between the cathodeelectrode 36 and a sealing layer 37. This is because the light emittinglayer 35 is vulnerable to humidity. Moisture is absorbed by thedesiccant to prevent deterioration of the light emitting layer 35.

An organic EL display 30 of the present invention shown in FIG. 6( b)has the present circular polarization plate 31, and in this apparatus, alight emitting layer 35 and a cathode electrode 36 are laminated on abase plate 32 carrying a pixel electrode 34 formed via an interlayerinsulation film 33. A sealing layer 37 is formed on the cathodeelectrode, and the present circular polarization plate 31 is disposed onthe side opposite to base plate 32. Light emitted from the lightemitting layer 35 permeates the cathode electrode 36, the sealing layer37 and the present circular polarization plate 31.

EXAMPLES

The present invention will be illustrated further in detail by examplesbelow. “%” and “parts” in examples are % by mass and parts by mass,unless otherwise stated.

As the cycloolefin polymer film (COP), ZF-14 manufactured by ZeonCorporation was used.

As the saponified triacetylcellulose film (TAC), KC4UY manufactured byKonica Minolta Inc. was used.

As the corona treatment apparatus, AGF-B10 manufactured by KasugaElectric Works Ltd. was used.

The corona treatment was conducted once under conditions of an output of0.3 kW and a treating speed of 3 m/min. using the above-described coronatreatment apparatus.

As the polarization UV irradiation apparatus, SPOT CURE SP-7 equippedwith polarizer unit manufactured by Ushio Inc. was used.

As the laser microscope, LEXT manufactured by Olympus Corporation wasused.

As the high pressure mercury lamp, UNICURE VB-15201BY-A manufactured byUshio Inc. was used.

The phase difference value was measured using KOBRA-WR manufactured byOji Scientific Instruments was used.

Example 1 [Preparation of Photo-Orientation Film Forming Composition]

The following components were mixed and the resultant mixture wasstirred at 80° C. for 1 hour, to obtain a photo-orientation film formingcomposition (1).

photo-orienting material (5 parts):

solvent (95 parts): cyclopentanone

[Preparation of Orienting Polymer Composition (1)]

To a commercially available orienting polymer SUNEVER SE-610(manufactured by Nissan Chemical Industries, Ltd.) was added2-butoxyethanol, to obtain an orienting polymer composition (1) having acomposition shown in Table 1.

[Preparation of Orienting Polymer Composition (2)]

To a commercially available polyvinyl alcohol (Polyvinyl Alcohol 1000perfectly saponified type, manufactured by Wako Pure ChemicalIndustries, Ltd.) was added water and the mixture was heated at 100° C.for 1 hour, to obtain an orienting polymer composition (2) having acomposition shown in Table 1.

TABLE 1 solid content solvent orienting polymer 1% 99% compoisition (1)orienting polymer 2% 98% composition (2)

The value in Table 1 represents the content proportion of each componentwith respect to the total amount of the prepared composition. RegardingSE-610, the solid content was converted from the concentration describedin the delivery specification.

[Preparation of a Composition (A-1)]

The following components were mixed and the resultant mixture wasstirred at 80° C. for 1 hour, to obtain a composition (A-1).

A polymerizable liquid crystal A1 and a polymerizable liquid crystal A2were synthesized by a method described in JP-A No. 2010-31223

Polymerizable Liquid Crystal A1 (80 parts):

Polymerizable Liquid Crystal A2 (20 parts);

Polymerization Initiator (6 parts);2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure369; manufactured by Ciba Specialty Chemicals) leveling agent (0.1part): polyacrylate compound (BYK-361N; manufactured by BYK-Chemie)solvent: cyclopentanone (400 parts)

[Preparation of Composition (B-1)]

The composition of a composition (B-1) is shown in Table 2. Componentswere mixed and the resultant solution was stirred at 80° C. for 1 hour,then, cooled down to room temperature, to obtain a composition (B-1).

TABLE 2 polymerizable polymer- liquid ization leveling reaction crystalinitiator agent additive solvent compo- LC242 Irg907 BYK-361N LR9000PGMEA sition (19.2%) (0.5%) (0.1%) (1.1%) (79.1%) (B-1)

The value in parentheses in Table 2 represents the content proportion ofeach component with respect to the total. amount of the prepared(Imposition. In Table 2, LR9000 represents Laromer registeredtrademark,.) LR-9000 manufactured: by BASF Japan, Irg907 representsIrgacure (registered trademark) 907 manufactured by BASF Japan, BYK361Nrepresents a leveling agent manufactured by BYK Chemie Japan, LC242represents polymerizable liquid crystal represented by the followingformula manufactured by BASF, and PGMEA represents propylene glycol1-monomethyl ether 2-acetate.

[Production of First Phase Difference Layer (1-1)]

A cycloolefin polymer film (COP) (ZF-14, manufactured by ZEONCorporation) was treated once under conditions of an output of 0.3 kWand a treating speed of 3 m/min using a corona treatment apparatus(AGF-B10, manufactured by Kasuga Electric works Ltd.). On the surfacehaving undergone the corona treatment, a photo-orientation film formingcomposition (1) was coated by a bar coater and dried at 80° C. for 1minute, and subjected to polarization UV exposure using a polarizationUV irradiation apparatus (SPOT CURE SP-7; manufactured by Ushio Inc.) atan accumulated light quantity of 100 mJ/cm². The thickness of theresultant orientation film was measured by a laser microscope (LEXT,manufactured by Olympus Corporation to find a value of 100 nm.Subsequently, a composition (A-1) was coated on the orientation filmusing a bar coater and dried at 120° C. for 1 minute, then, irradiatedwith ultraviolet (under nitrogen atmosphere, wavelength: 365 nm,accumulated light quantity at a wavelength of 365 nm: 1000 mJ/cm²) usinga high pressure mercury lamp (UNICURE VB-15201BY-A, manufactured byUshio Inc.) to form a first phase difference layer (1-1), obtaining aphase difference film (1). The phase difference value of the resultantphase difference film (1) was measured to find that Re(550)=138 nm,Rth(550)=62 nm. Further, the phase difference values at a wavelength of450 nm and a wavelength of 650 nm were measured, to find thatRe(450)=121 nm, Re(650)=141 nm. The relationship of in-plane phasedifference values at respective wavelengths is as described below.

Re(450)/Re(550)=0.87

Re(650)/Re(550)=1.02

That is, the first phase difference layer (1-1) had optical propertiesrepresented by the following formulae (1) (2) and (4). Since the phasedifference value at a wavelength of 550 nm of COP is approximately 0, itdoes not affect the relationship of the in-plane phase differencevalues.

Re(450)/Re(550)≦1.00  (1)

1.00≦Re(650)/Re(550)  (2)

100<Re(550)<160  (4)

[Production of Second Phase Difference Layer (2-1)]

The surface of COP was treated once under conditions of an output of 0.3kW and a treating steed of 3 m/min using a corona treatment apparatus.On the surface having undergone the corona treatment, an orientingpolymer composition (1) was coated using a bar coater, dried at 90° C.for 1 minute, to obtain an orientation film. The thickness of theresultant orientation film was measured by a laser microscope, to find avalue of 34 nm. Subsequently, a composition (B-1) was coated on theorientation film using a bar coater, and dried at 90° C. for 1 minute,then, irradiated with ultraviolet (under nitrogen atmosphere,accumulated quantity at a wavelength of 365 nm: 1000 mJ/cm²) using ahigh pressure mercury lamp to form a second phase difference layer(2-1), obtaining a phase difference film (2). The thickness of theresultant second phase difference layer (2-1) was measured b a lasermicroscope, to find a value of 450 nm. Further, the phase difference ata wavelength of 550 nm of the resultant phase difference film (2) wasmeasured, to find that Re(550)=1 nm, Rth(550)=−70 nm. That is, thesecond phase difference layer (2-1) had an optical property representedby the following formula (3). Since the phase difference value at awavelength of 550 nm of COP is approximately 0, it does not affect theoptical property.

n _(x) ≈n _(y) <n _(a)  (3)

[Production of Optical Film (1)]

In the same manner as for production of the first phase difference layer(1-1), a first phase difference layer was formed on COP to obtain afirst phase difference layer (1-2). Next, the surface of the first phasedifference layer (1-2) was treated with corona, then, in the same manneras for production of the second phase difference layer (2-1), a secondphase difference layer (2-2) was formed. That is, an optical film (1)having COP, the first phase difference layer (1-2) and the second phasedifference layer (2-2) laminated in this order was obtained. The phasedifference value of the resultant optical film (1) at a wavelength of550 nm was measured, to find that Re(550)=138 nm, Rth(550)=1.4 nm.Further, the phase difference values at a wavelength of 450 nm and awavelength of 650 nm were measured, to find that Re(450)=122 nm,Re(650)=141 nm. The relationship of in-plane phase difference values atrespective wavelengths is as described below.

Re(450)/Re(550)=0.88

Re(550)/Re(550)=1.02.

That is, the optical film (1) had optical properties represented by thefollowing formulae (1) and (2).

Re(450)/Re(550)≦1.00  (1)

1.00≦Re(650)/Re(550)  (2)

Example 2 [Production of Layer A (A-1)]

On a saponified triacetylcellulose film (TAC) manufactured by KonicaMinolta Inc., KC4UY), an orienting polymer composition (2) was coated,heated to dry, then, a film of an orienting polymer having a thicknessof 82 nm was formed. On the resultant surface of the film of anorienting polymer, a rubbing treatment was performed at an angle of 15°from the longitudinal direction of the above-described TAC, and acomposition (B-1) was coated thereon using a bar coater, dried at 100°C. for 1 minute, then, irradiated with ultraviolet (under nitrogenatmosphere, accumulated light quantity at a wavelength of 365 nm: 1200mJ/cm²) using a high pressure mercury lamp, to form a layer A (A-1). Thethickness of the resultant layer A (A-1) was measured by a lasermicroscope, to find a value of 973 nm, The phase difference value of theresultant layer A(A-1) was measured, to find that Re(550)=135 nm, andthe orientation angle was 15° to the longitudinal direction of TAC.Further, the phase difference values at a wavelength of 450 nm and awavelength of 650 nm were measured, to find that Re (450)=145 nm,Re(650)=132 nm. The relationship of in-plane phase difference values atrespective wavelengths is as described below.

Re(450)/Re(550)=1.07

Re(650)/Re(550)=0.98

That is, the layer A (A-1) had optical properties represented by thefollowing formulae (4), (6) and (7).

100<Re(550)<160  (4)

Re(450)/Re(550)≧1.00  (6)

1.00≧Re650)/Re(550)  (7)

[Production of Layer B (B-1)]

An orienting polymer composition (2) was coated on TAC, heated to dry,then, a film of an orienting polymer having a thickness of 80 nm wasobtained. On the surface of the resultant orienting polymer film, arubbing treatment was performed at an angle of 75° from the longitudinaldirection of the above-described TAC, and a composition (B-1) was coatedon this using a bar coater, dried at 100° C. for 1 minute, then,irradiated with ultraviolet (under nitrogen atmosphere, accumulatedlight quantity at a wavelength of 365 nm: 1200 mJ/cm²) using a highpressure mercury lamp, to form a layer B(B-1). The thickness of theresultant layer B (B-1) was measured by a laser microscope, to find avalue of 1.94 μm. The phase difference value of the resultant layerB(B-1) was measured, to find that Re(550)=269 nm, and the orientationangle was 75° to the longitudinal direction of TAC. Further, the phasedifference values at a wavelength of 450 nm and a wavelength of 650 nmwere measured, to find that Re(450)=290 nm, Re(650)=265 nm. therelationship of in-plane phase difference values at respectivewavelengths is as described below.

Re(450)/Re(550)=1.08

Re(650)/Re(550)=0.99

that is, the layer B (B-1) had optical properties represented by thefollowing formulae (5), (6) and (7).

200<Re(550)<320  (5)

Re(450)/Re(550)≧1.00  (6)

1.00≧Re(650)/Re(550)  (7)

[Production of Optical Film (2)]

In the same manner as for production of the layer A (A-1) a layer A wasformed on TAC, to obtain a layer A (A-2). On the resultant layer A(A-2), a corona treatment was performed, then, in the same manner as forproduction of the layer B (B-1), a layer B (B-2) was formed on the layerA (A-2). Subsequently, the COP surface of the phase difference film (2)fabricated in Example 1 was pasted to the surface of the resultant layerB (B-2) using a sticky agent, to fabricate an optical film (2).Therefore, the optical film (2) has a laminated structure in which theslew axis of the layer A (A-2) makes an angle of 15° and the slow axisof the layer B(B-2) makes an angle of 75° to the longitudinal directionof the above-described TAC. The phase difference value of the resultantoptical film (2) was measured, to find that Re(550)=37 nm, Re(450)=nm,Re(650)=160 nm. The relationship of in-plane phase difference values atrespective wavelengths is as described below.

Re(450)/Re(550)=0.73

Re(650)/Re(550)=1.17

That is, the optical film (2) had optical properties represented by theformulae (1) and (2).

Example 3 [Production of Polarizer]

A polyvinyl alcohol film having an average degree of polymerization ofabout 2400, a degree of saponification of 99.9 mol % or more and athickness of 75 μm was immersed in pure water of 30° C., then, immersedin an aqueous solution containing iodine/potassium iodide/water at aweight ratio of 0.02/2/100 at 30° C. to effect iodine dyeing (iodinedyeing step). The polyvinyl alcohol film after the iodine dyeing stepwas immersed in an aqueous solution containing potassium iodide/boricacid/water at a weight ratio of 12/5/100 at 56.5° C. to effect a boricacid treatment (boric acid treatment step). The polyvinyl alcohol filmafter the boric acid treatment step was washed with pure water of 8° C.,then dried at 65° C., to obtain a polarizer (thickness after drawing, 27um) in which iodine was adsorbed and oriented in the polyvinyl alcohol.In the iodine dyeing step and the boric acid treatment step, drawing wasconducted. The total drawing magnification in such drawing operationswas 5.3 time. The resultant polarizer and the saponifiedtriacetylcellulose film (manufactured by Konica Minolta Inc. KC4UYTAC 40μm) were pasted together via an aqueous adhesive by nip rolls. Theresultant pasted material was dried at 60° C. for 2 minutes whilekeeping the tension thereof at 430 N/m, to obtain a polarization plate(1) having the triacetylcellulose film as a protective film on onesurface. The above-described aqueous adhesive was prepared by adding 3parts of a carboxyl group-modified polyvinyl alcohol (manufactured byKuraray Co., Ltd., Kuraray POVAL KL318) and 1.5 parts of a water-solublepolyamide epoxy resin (manufactured by Sumika Chemtex Co., Ltd., SumirezResin 650, aqueous solution having a solid concentration of 30%) to 100parts of water.

[Production of Ultraviolet Curable Adhesive Composition]

The following component were mixed to prepare an ultraviolet curableadhesive composition.

3,4-epoxycyclohexylmethyl 40 parts 3,4-epoxycyclohexanecarboxylatediglycidyl ether of bisphenol A 60 partsdiphenyl(4-phenylthiophenyl)sulfonium  4 parts hexafluoroantimonate(photo-cation polymerization initiator)

[Production of Circular Polarization Plate (1)]

On the surface of the second phase difference layer of the optical film(1) produced in Example 1, a corona treatment was performed, anultraviolet curable adhesive composition was coated thereon, and thepolarizer surface of the polarization plate (1) was superimposed on thisand allowed to pass through between two laminating rolls to attainintegration. Here, the absorption axis of the polarization plate (1) andthe slow axis of the first phase difference layer (1-2) made an angle45°. Of the two lamination rolls, a rubber roll having the surface madeof rubber was used as the first lamination roll, and a metal roll havingthe surface having undergone chromium plating was used as the secondroll. After lamination, the COP surface of the above-described opticalfilm (1) was irradiated with ultraviolet using an ultravioletirradiation apparatus having a metal halide lamp as a light source sothat the accumulated light quantity at a wavelength from 3200 to 400 nmwas 20 mJ/cm², thereby curing of the adhesive to attain adhesion to thepolarization plate (1), obtaining a circular polarization plate (1).

Example 4 [Production of Circular Polarization Plate (2)]

In the same manner as in Example 3, the TAC surface of the optical film(2) produced in Example 2 was treated with corona, then, thepolarization plate (1) was pasted onto this using the same aqueousadhesive as used in production of the polarization plate (1), to obtaina circular polarization plate (2). In this case, pasting was controlledso that the angle made by the absorption axis of the polarization plate(1) and the axis of the layer B (B-2) of the optical film (2) was 75°and the angle made by the absorption axis of the polarization plate (1)and the slow axis of the layer A (A-2) was 15°.

Comparative Example [Production of Second Phase Difference Layer (2-2)]

In the same manner as for production of the second phase differencelayer (2-1) in Example 1, a second phase difference layer was formed onCOP to obtain a second phase difference layer (2-3). The phasedifference value of the resultant second phase difference layer (2-3) ata wavelength of 550 nm was measured, to find that Re(550)=1 nm,Rth(550)=−247 nm. The thickness of the resultant second phase differencelayer (2-3) was measured by a laser microscope, to find a value of 1600nm.

[Production of Comparative Optical Film]

In the same manner as for production of the first phase difference layer(1-1), a first phase difference layer (1-2) was formed on COP, to obtaina first phase difference layer (1-2). The surface of the resultant firstphase difference layer (1-2) was treated with corona, then, a secondphase difference layer (2-4) was formed thereon by the same method asfor production of the second phase difference layer (2-3). That is, acomparative optical film having COP, the first phase difference layer(1-2) and the second phase difference layer (2-4) laminated in thisorder was obtained.

[Production of Comparative Circular Polarization Plate]

In the same manner as for production of the circular polarization plate(1) in Example 3, a comparative optical film (1) and a polarizationplate (1) were pasted, to obtain a comparative circular polarizationplate. Also in the comparative circular polarization plate, pasting wascontrolled so that the angle made by the absorption axis of thepolarization plate (1) and the slow axis of the first phase differencelayer (1-2) was 45°.

Reference Example 1

The COP surface of the phase difference film (1) and the polarizationplate (1) were pasted, to obtain a circular polarization plate(Reference 1). In this case, pasting was controlled so that the anglemade by the absorption axis of the polarization plate (1) and the slowaxis of the phase difference film (1) was 45°.

Reference Example 2

A layer A was formed on COP in the same manner as for production of thelayer A (A-1) in Example 2 excepting that TAC was replaced by COP, toobtain a layer A (A-14). The above-described layer A (A-14) had a slowaxis at an angle of 15° from the longitudinal direction of theabove-described COP. The surface of the resultant layer A (A-14) wastreated with corona, then, an orienting polymer composition (1) wascoated thereon using a bar coater, and dried at 90° C. for 1 minute, toform an orientation film. On the resultant orientation film, acomposition (B-1) was coated using a bar coater, dried at 90° C. for 1minute, then, irradiated with ultraviolet (under nitrogen atmosphere,accumulated light quantity at a wavelength of 365 nm: 1000 mJ/cm²) usinga high pressure mercury lamp, to form a second phase difference layer(2-16). Subsequently, the surface opposite to the surface on which thelayer A (A-14) had been formed of the above-described COP was treatedwith corona, and a polarization plate (1) was pasted onto this using anultraviolet curable adhesive composition, to obtain a circularpolarization plate (Reference 2). In this case, pasting was controlledso that the angle made by the absorption axis of the polarization plate(1) and the slow axis of the above-described layer A (A-14) was 45°.

Reference Example 3

A layer B was formed on COP in the same manner as for production of thelayer B (B-1) in Example 2 excepting that TAC was replaced by COP, toobtain a layer B(B-14). The above-described layer B (B-14) had a slowaxis at an angle of 75° from the longitudinal direction of theabove-described COP. The surface of the resultant layer B (B-14) wastreated with corona, then, an orienting polymer composition (1) wascoated thereon using a bar coater, and dried at 90° C. for 1 minute, toform an orientation film. On the resultant orientation film, acomposition (B-1) was coated using bar coater, dried at 90° C. for 1minute, then, irradiated with ultraviolet (under nitrogen atmosphere,accumulated light quantity at a wavelength of 365 nm: 1000 mJ/cm²) usinga high pressure mercury lamp, to form a second phase difference layer(2-17). Subsequently, the surface opposite to the surface on which thelayer B (B-14) had been formed of the above-described COP was treatedwith corona, and a polarization plate (1) was pasted onto this using anultraviolet curable adhesive composition, to obtain a circularpolarization plate (Reference 3). In this case, pasting was controlledso that the angle made by the absorption axis of the polarization plate(1) and the slow axis of the above-described layer B (B-14) was 45°.

Reference Example 4

A layer A was formed on COP in the same manner as for production of thelayer A (A-1) in Example 2 excepting that TAC was replaced by COP, toobtain a layer A (A-15). The above-described layer A (A-16) had a slowaxis at an angle of 15° from the longitudinal direction of theabove-described COP The surface of the resultant layer A (A-15) wastreated with corona, then, an orienting polymer composition (2) wascoated thereon using a bar coater, and dried at 100° C. for 1 minute. Onthe surface of the dried orienting polymer, a rubbing treatment wasperformed at an angle of 75° C. from the longitudinal direction of theabove-described COP, a composition (B-1) was coated thereon using a barcoater, dried at 100° C. for 1 minute, then, irradiated with ultraviolet(under nitrogen atmosphere, accumulated lint quantity at a wavelength of365 nm: 1200 mJ/cm²) using a high pressure mercury lamp, to form a layerB(B-16). Subsequently, the surface opposite to the surface on which thelayer A (A-15) had been formed of the above-described COP was treatedwith corona, then, a polarization plate (1) was pasted onto this usingan ultraviolet curable adhesive composition, to obtain a circularpolarization plate (Reference 4).

The surface opposite to the polarization plate (1) of the circularpolarization plates (1), (2) and the comparative circular polarizationplate obtained in Examples 3 to 4 and the circular polarization plates(Reference 1) to (Reference 4) obtained in Reference Examples 1 to 4 waspasted to a mirror using a pressure-sensitive sticky agent. The pastedcircular polarization plate was observed from observed from all azimuthdirections at a position of an elevation angle of 60° from the frontvertical direction. Colors viewed from 2 directions at which hue changewas particularly large are shown in Table 3. Both the circularpolarization plates (1) and (2) revealed no coloration and showedexcellent black display when observed from any direction.

TABLE 3 observation observation constitution of circular polarizationplate direction 1 direction 2 reference polarization COP first phase — —green red example 1 plate difference layer reference polarization COPlayer A second phase — white white example 2 plate difference layerreference polarization COP layer B second phase — white white example 3plate difference layer reference polarization COP layer A layer B — bluegreen example 4 plate circular polarization first phase first phase COP— first phase black black polarization plate difference differencedifference plate 1 layer layer layer (2-1) (2-1) circular polarizationCOP layer A layer B COP black black polarization plate plate 2comparative polarization second phase first phase COP — white whitecircular plate difference difference polarization layer layer plate(2-2)

Also from the above-described results of measurement, it is understoodthat the circular polarization plates of the examples are excellent inan anti-reflection property in bright place when observed from anydirections, and useful.

INDUSTRIAL APPLICABILITY

The optical film of the present invention is useful as an optical filmexcellent in suppression of light leakage in black display.

EXPLANATION OF REFERENCES

1 first phase difference layer2 second phase difference layer3, 3′ base plate100 present optical film4 layer A5 layer B6 polarization plate8 third phase difference layer7 organic EL panel110 present circular polarization plate200 organic EL display30 organic EL display31 present circular polarization plate32 base plate33 interlayer insulation film34 pixel electrode35 light emitting layer36 cathode electrode37 sealing layer38 this film transistor39 rib

1. An optical film having a first phase difference layer and a secondphase difference layer, wherein the second phase difference layer has anoptical property represented by the formula (3), the second phasedifference layer has a thickness of 0.2 μm to 2.0 μm, and further, theoptical film has optical properties represented by the formula (1) andthe formula (2):Re(450)/Re(550)≦1.00  (1)1.00≦Re(650)/Re(550)  (2)nx≈ny<nz  (3) wherein, Re(450) represents the in-plane phase differencevalue at a wavelength of 450 nm, Re(550) represents the in-plane phasedifference value at a wavelength of 550 nm, and Re(650) represents thein-plane phase difference value at a wavelength of 650 nm, nx representsthe principal refractive index in a direction parallel to the film planein an index ellipsoid formed by the phase difference layer, nyrepresents the refractive index in a direction parallel to the filmplane and orthogonally-crossing the direction of the principalrefractive index in an index ellipsoid formed by the phase differencelayer, nz represents the refractive index in a direction vertical to thefilm plane in an index ellipsoid formed by the phase difference layer.2. The optical film according to claim 1, wherein the first phasedifference layer has an optical property represented by the formula (4):100<Re(550)<160  (4) wherein, Re(550) represents the same meaning asdescribed above.
 3. The optical film according to claim 1, wherein thefirst phase difference layer has optical properties represented by theformula (1) and the formula (2):Re(450)/Re(550)<1.00  (1)1.00≦Re(650)/Re(550)  (2) wherein, Re(450), Re(550) and Re(650)represent the same meaning as described above.
 4. The optical filmaccording to claim 1, wherein the first phase difference layer has alayer A having optical properties represented by the formulae (4), (6)and (7) and a layer B having optical properties represented by theformulae (5), (6) and (7):100<Re(550)<160  (4)200<Re(550)<320  (5)Re(450)/Re(550)≧1.00  (6)1.00≧Re(650)/Re(550)  (7) wherein, Re(450), Re(550) and Re(650)represent the same meaning as described above.
 5. The optical filmaccording to claim 1, further having a third phase difference layer,wherein the third phase difference layer has an optical propertyrepresented by the formula (5):200<Re(550)<320  (5) wherein, Re(550) represents the same meaning asdescribed above.
 6. The optical film according to claim 5, wherein thefirst phase difference layer and the third phase difference layer haveoptical properties represented by the formula (6) and the formula (7):Re(450)/Re(550)≧1.00  (6)1.00≧Re(650)/Re(550)  (7) wherein, Re(450), Re(550) and Re(650)represent the same meaning as described above.
 7. The optical filmaccording to claim 5, wherein third phase difference layer is a coatinglayer formed by polymerizing at least one polymerizable liquid crystal.8. The optical film according to claim 5, wherein the third phasedifference layer has a thickness of 5 μm or less.
 9. The optical filmaccording to claim 5, wherein the third phase difference layer is formedon an orientation film.
 10. The optical film according to claim 1,wherein the first phase difference layer is a coating layer formed bypolymerizing at least one polymerizable liquid crystal.
 11. The opticalfilm according to claim 1, wherein the second phase difference layer isa coating layer formed by polymerizing at least one polymerizable liquidcrystal.
 12. The optical film according to claim 1, wherein the firstphase difference layer has a thickness of 1.0 μm to 7.5 μm.
 13. Theoptical film according to claim 1, wherein the second phase differencelayer has a thickness of 0.3 μm to 1.0 μm.
 14. The optical filmaccording to claim 1, wherein each of the first phase difference layerand the second phase difference layer has a thickness of 2.0 μm or less.15. The optical film according to claim 1, wherein the first phasedifference layer is formed on an orientation film.
 16. The optical filmaccording to claim 1, wherein the second phase difference layer isformed on an orientation film.
 17. The optical film according to claim9, wherein the orientation film is an orientation film having anorientation regulation force generated by photoirradiation.
 18. Theoptical film according to claim 9, wherein the orientation film is anorientation film generating a vertical orientation regulation force. 19.The optical film according to claim 15, wherein the orientation film hasa thickness of 500 nm or less.
 20. The optical film according to claim1, wherein the first phase difference layer is formed via or not via anorientation film on a base material, and the second phase differencelayer is formed via or not via an orientation film on the first phasedifference layer.
 21. The optical film according to claim 1, wherein thesecond phase difference layer is formed via or not via an orientationfilm on a base material, and the first phase difference layer is formedvia or not via an orientation film on the second phase difference layer.22. The optical film according to claim 5, wherein having the firstphase difference layer, the second phase difference layer and the thirdphase difference layer in this order.
 23. The optical film according toclaim 20, wherein having a protective layer between the first phasedifference layer and the second phase difference layer.
 24. The opticalfilm according to claim 22, wherein having a protective layer betweenthe second phase difference layer and the third phase difference layer.25. The optical film according to claim 1, wherein the first phasedifference layer is formed via or not via an orientation film on onesurface of a base material, and the second phase difference layer isformed via or not via an orientation film on the other surface of a basematerial.
 26. The optical film according to claim 4, wherein the layer Ais a coating layer formed by polymerizing at least one polymerizableliquid crystal.
 27. The optical film according to claim 4, wherein thelayer B is a coating layer formed by polymerizing at least onepolymerizable liquid crystal.
 28. The optical film according to claim 4,wherein the layer A has a thickness of 0.5 μm to 2.5 μm.
 29. The opticalfilm according to claim 4, wherein the layer B has a thickness of 0.5 μmto 5.0 μm.
 30. The optical film according to claim 4, wherein each ofthe layer A and the layer B has a thickness of 2.5 μm or less.
 31. Theoptical film according to claim 4, wherein the layer A is formed via ornot via an orientation film on a base material, the layer B is formedvia or not via an orientation film on the layer A, and the second phasedifference layer is formed via or not via an orientation film on thelayer B.
 32. The optical film according to claim 4, wherein the layer Bis formed via or not via an orientation film on a base material, thelayer A is formed via or not via an orientation film on the layer B, andthe second phase difference layer is formed via or not via anorientation film on the layer A.
 33. The optical film according to claim4, wherein the second phase difference layer is formed via or not via anorientation film on a base material, the layer A is formed via or notvia an orientation film on the second phase difference layer, and thelayer B is formed via or not via an orientation film on the layer A. 34.The optical film according to claim 4, wherein the second phasedifference layer is formed via or not via an orientation film on a basematerial, the layer B is formed via or not via an orientation film onthe second phase difference layer, and the layer A is formed via or notvia an orientation film on the layer B.
 35. The optical film accordingto claim 4, wherein the layer A is formed via or not via an orientationfilm on one surface of a base material, the layer B is formed via or notvia an orientation film on the layer A, and the second phase differencelayer is formed via or not via an orientation film on the other surfaceof a base material.
 36. The optical film according to claim 4, whereinthe layer B is formed via or not via an orientation film on one surfaceof a base material, the layer A is formed via or not via an orientationfilm on the layer B, and the second phase difference layer is formed viaor not via an orientation film on the other surface of a base material.37. The optical film according to claim 31, wherein having a protectivelayer between the layer A and the layer B.
 38. The optical filmaccording to claim 5, wherein the first phase difference layer is formedvia or not via an orientation film on a base material, the second phasedifference layer is formed via or not via an orientation film on thefirst phase difference layer, and the third phase difference layer isformed via or not via an orientation film on the second phase differencelayer.
 39. The optical film according to claim 5, wherein the thirdphase difference layer is formed via or not via an orientation film on abase material, the second phase difference layer is formed via or notvia an orientation film on the third phase difference layer, and thefirst phase difference layer is formed via or not via an orientationfilm on the second phase difference layer.
 40. The optical filmaccording to claim 5, wherein the first phase difference layer is formedvia or not via an orientation film on one surface of a base material,the second phase difference layer is formed via or not via anorientation film on the first phase difference layer, and the thirdphase difference layer is formed via or not via an orientation film onthe other surface of a base material.
 41. The optical film according toclaim 5, wherein the second phase difference layer is formed via or notvia an orientation film on one surface of a base material, the firstphase difference layer is formed via or not via an orientation film onthe second phase difference layer, and the third phase difference layeris formed via or not via an orientation film on the other surface of abase material.
 42. The optical film according to claim 5, wherein thethird phase difference layer is formed via or not via an orientationfilm on one surface of a base material, the second phase differencelayer is formed via or not via an orientation film on the third phasedifference layer, and the first phase difference layer is formed via ornot via an orientation film on the other surface of a base material. 43.The optical film according to claim 5, wherein the second phasedifference layer is formed via or not via an orientation film on onesurface of a base material, the third phase difference layer is formedvia or not via an orientation film on the second phase difference layer,and the first phase difference layer is formed via or not via anorientation film on the other surface of a base material.
 44. A circularpolarization plate having the optical film according to claim 1 and apolarization plate.
 45. The circular polarization plate according toclaim 44, wherein the optical film and the polarization plate are pastedtogether with an active energy ray curable adhesive or an aqueousadhesive.
 46. An organic EL display having the circular polarizationplate according to claim
 44. 47. A touch panel display having thecircular polarization plate according to claim 44.